http://www.vgchartz.com/article/258660/uk-pc-digital-market-hit-741-million-in-2014-retail-market-shrinks/

Digital market for console is about 10% for, PC is about 95% for UK.

I bought the digital version on PS4 so me and my GF could play GTA Online together with one copy of the game.

With the preorders, the day-1 sales and the huge size of the game, will Steam and other digital distribution platforms be able to handle the traffic?

1-3% on top of retail, I'm guessing. It's a pretty large file size, so most likely went ahead and purchase the disc.

Really no bluray drive or dvd drive?

You have a CD drive? wow    keep that thing its antique  its history haha

I think digital is pretty high and rather significant. My NextGen friends pretty much all by only digitally - unless they are on a WiiU.

Can someone look it up on say Amazon and see the sales?

But that excludes people that buy it directly through a digital sale or something. I'll get it once it goes on a big sale digitally. So many games to play in the meantime though.

We need to find a way to track digital or VGChartz will only be for the 'old traditional' people who buy physical media.

i think it sold pretty well on digital

what others have said. 10% digital sales are fairly typical for console games.

Also is the retail PC version really on that many discs? No wonder digital sales are much higher there. It's only getting more ridiculous unless Bluray drives will take off in the future (which I really doubt).

45 million includes copies sold to retail and end users via digital download.

I'm expecting this to exceed 50 million shortly due to the PC release and eventually I'd even expect to see more than 60 million units sold. 

Yeah, it should be no problem. Dota2 has around 700,000 - 1,000,000 concurrent players, this game has around 180,000 - 320,000 concurrent. Also Steam lets people download the game days before release so that should not have been an issue.