It depends on two things really. I love Killzone SF, but it was a true launch title. Solid gameplay with pretty visuals and nothing really new to bring to the table. The game was rushed and it shows with the lack of voice chat and clan system (voice is there now, I think clans are as well if not close). Furthermore I feel like the lack of sup 1080p multiplayer was more because of this than anything else as well. From the start, it was incomplete. The story was actually very good in the SP, but it was crippled by that fact that there were no interesting characters to deliver the full potential of the lore that surrounded the game (some people still don't get what it was REALLY about).

Titanfall on the other hand is MP only, so SF single player mode flaws are really moot for those looking to play TF. The first thing that would need to happen is that Titanfall would have to have good reception (the hype for it will either make OR break this game). It tips it's hat to CoD players which could help paired with the fact that it is actually innovative and fresh. Regardless of reception, I'm sure it will be a good game at the very least.

The other is that it has to move consoles. The fact that the 360 is also getting a version is really hurtful here. As it stands now, more than half of the X1 install base will have to buy this game for it to beat SF in sales (not everyone wants this game, many will rent just to try it out). Titanfall will have to move consoles in order to stand a remote chance of beating it out. One advantage it does have though, unlike SF, is it isn't being released alongside of two FPS juggernauts (CoD and BF).

If BOTH of these things happen, and they MIGHT, it could pass SF in sales for X1. 360 sales however I am almost sure will pass SF unless the game totally tanks.

Just my 2 cents.

EDIT:

Another advantage to X1 sales is that Titanfall is the only big name exclusive that will be out at 2014 at this point, therefore most X1 owners will feel more tempted to try it.  SF was a rushed launch title and probably won't see too many extreme sales as the PS4 has four other big name AAA exclusives coming out in 2014 (Driveclub, Infamous SS, The Order, MLB The Show 2014).  That said people on the PS4 will be focusing on these newer titles when it comes to exclusive games while Titanfall will have the spotlight on the X1 (at least for those don't want to play it on the 360).

That's one of the most awesome gifs I have ever seen, thanks!

About the topic: Yeah, probably. But mainly because of the much bigger install base. I mean, PS4 numbers is very likely gonna double those of X1 before summer. So it's not really a fair battle.

This is hilarious

Some pretty decent preorder numbers for Titanfall there, pal?

Personally I think Killzone SF is going to be a better all around game than Titanfall, but that being said, Xbox owners tend to love their first person shooters and even if it doesnt move many consoles right away, I see the Xbox One version outselling Killzone SF in the long run

I think it will... What else does the 3.5 million X1 fans have to play?

This will be interesting.

TF on xb1 will outsell KZSF and out score it aswell

TF LT sales will also double KZSF LT as early as years end

thats shipped dude, as seen by VGCs numbers still at 1.4M yes eventually they sell all that 2.1M but TF will probably ship 2M by the end of the month latest end of april

Without doubt.

Edited: Killzone will stop around 3.5m, TitanFall around 5m (Lifetime).