look at gta on the ds vs psp for your answer

Yes. Because software sells hardware. Therefore, the fanbase will be buying the Wii U to play it.

13 million people wouldnt buy a WiiU for GTA

Nah, completely wrong demographic.

It wouldn't push 15 million.

But it would sell like 3-4 million of consoles, yeah it would.

Definitely. GTA is one of those franchises that i it were a Wii U exclusive, people would be clawing over each other to get both the console and game.
Even if it were just released as a port, I have no doubt that the game would have sold over a million, so long as it had features that would entice people to get the Wii U version.

If it were exclusive it would have insanely pushed the Wii U sales.

It wouldn't sell the PS360 numbers, cause not everyone would be willing to buy a game for 350$ to play, but I guess it would shift around 5 million Wii Us exclusively thanks to GTA V.

If GTA V was a Wii U exclusive and used the gamepad remarkably then it would definitely sell a ton but not more then it would've as its on PS360.

If GTA V was a Wii U exclusive with just regular gameplay then it would still shift quite a bit (since its GTA unlike Bayonetta) but then you'll have people being upset and all "wtf does it need to be Wii U exclusive" when it can do the same on other consoles that's more suited for GTA

the psp version of china town wars was a 6month late port yet look how it sold compared to the ds version