To answer this question I take a time machine back to April 2007. PS3 started in Europe in March, so I thought this would be a fair time.

http://www.vgchartz.com/weekly/39201/Global/

X360: 9,680,260

PS3: 3,236,080

But to be fair, at this time the lead of the X360 was growing. The XBOX sold more at this time on a weekly base. Some later time the PS3 turned this around.

A 3m lead is nothing for an entire years worth of extra sales. Put the PS3 and 360 in an aligned launch and it shows, the only reason the 360 has a 3m lead currently is because it's been out longer. Other than that the PS3 has outsold the 360.

360 isn't ahead because it came first, its ahead because Sony released a $600 console. if PS3 launched at about $300 - $400. It would have easily surpassed the 360 and there would be no talk of this launch difference.

Sony just had to deliver Bluray and what do they have to show for it? Sharper video and games that don't use multiple discs? Totally worth hurting the Playstation brand.

Launching before the successor to a market leading console has generally translated into a growing userbase and increased marketshare, while launching significantly later than the successor to a market leading console has generally translated into a shrinking userbase and decreased marketshare.

I can use the same excuses too: PS3 is catching on to the 360 despite costing more, not selling in the biggest market(NA), and despite all the effort of the media bashing the PS3 its doing pretty good. Not to mention it closed a 6 million gap. What makes you think it won't close a 2.8 million gap lol? The 360 may have kept its lead, but its going down week after week, month after month. Its probably around 20 months before nextxbox/PS4 will launch, by that time PS3 will catch on. And yes, people will care, because consoles don't stop selling after a new one comes out, especially not with all the sales drama and fanboyism that arose this gen. People won't forget the "ps3 dont no sell", just like people didn't forget "ps3 dont have no gaemz". It will all backfire to them. :)

Coming out first absolutely affects it, but it's obviously not a surefire guarantee.

In each generation where the victor was the earlier one to release, they developed a significant foothold before the competition even released.

NES vs SEGA Master System.

GameBoy vs Game Gear.

Playstation vs N64 and Saturn.

PS2 vs GCN and Xbox (minus DC, which died off for separate reasons)

DS vs PSP.

In each of these cases, the earlier system to release was the system to win. It had already built itself a strong lead over the competition prior to the competition's release, with developers already setting strong plans for them and the system already developing a strong reputation amongst consumers.

But that obviously can't be the only thing. There have to be other factors to include as well, and ones that are much stronger than JUST "releasing first".

NES had the fact that it was vastly superior to anything previously released. It had graphics that could be recognized as actual shapes, not the stupid "block people" that you got on Atari games and the lot. It offered the experience of the arcade... at home!

GameBoy did similar things to the NES - provided never-before-seen handheld gaming. Before the GameBoy, you had Tiger or Game-and-Watch experiences on handhelds. Trash. GameBoy offered gaming on a level similar to home consoles... and with a brand-name that had taken the world by storm!

Playstation was a freaking CD player that also played THREE DIMENSIONAL videogames. HUGE concept in the early/mid 1990s.

Playstation 2 offered vastly upgraded graphics, was a DVD player (which was a huge thing in 2000), AND had the immense reputation of the Playstation to ride on. This is probably the weakest example on this list, but it also had kinda lousy competition, so it didn't NEED a very strong argument.

Then the DS vs PSP. DS was riding with the reputation of the Nintendo handheld brand, Nintendo's IPs, and now true 3D handheld graphics. It MADE handheld gaming a serious concept again, no longer just the "kid's time waster". PSP helped do the exact same thing, but it didn't have the handheld branding, it didn't have the IPs, and it didn't have the touchscreen. It was also bulkier.

None of the recent first releases (3DS, WiiU) have the same special tricks to take their leads. 3DS has the 3D gimmick, which is nice but won't take it that far. WiiU has the touchscreen, but that's nothing new to gaming so it won't make a huge difference. They BOTH need more than just their special gimmicks and releasing first to guarantee their lead this time. This generation, it's just not quite enough.

The Xbox360 was first to come out but not the most successful. The PS2 was first to come out and the most successful. The Dreamcast was first and you know the story. But I think it will come down to the attractiveness and pricing. Like most would look past the Wii U if it don't get the third party games this time around is what I mean by attractiveness. But it might be attractive from pricing being it will not have a Hard Drive (HD) and will most likely be cheaper, if the other consoles don't follow Nintendo footsteps. But I think the other consoles will have (HD), and can make Nintendo's console attractive that way.

 Xbox360 was first

 Nintendo Wii was second

Playstation 3 was third

Nothing, see Saturn, Dreamcast etc.