Answer 3 for me. Partly because of the 2 million or so the PS3 will get from Japan. But that's not all.

PlayStation has been the home of Final Fantasy for several years, and five games (not counting FF11, of course). So, it will have a better attach rate than the 360 version. I would say in North America, the 360 would have a slight lead, perhaps 500k units. By the time FF13 releases in Europe, I would say the PS3 would have overtaken the 360 in Europe, so FF13 should sell far better on the PS3 than the 360. Perhaps 1 million better on PS3.

GTA4 on PS3 in Europe actually outsold the 360 version.

So a 2 million lead from Japan, a 1 million lead from Europe and I would say a maximum 1 million loss in NA leads to 2 million extra sales.

It's all up in the air of course. It depends on userbase, attach rates, and of course the actual QUALITY of the game. I would say Answer 1 or 3, with 3 being ever so slightly more likely. 2 is less likely still, and 4...impossible.

Answer 1.
But in Japan can sell 2 million
in other can sell more.

Just in america FFXIII for xbox 360 can sell more.

Come FF 13 release date, we'll see ;)  If we go by PS2 attach rates on first week (FF 10 did 40% first week alone), then FF 13 will do 800,000k+ first week if released now.  I'm willing to bet attach rate will be about 50% first week because PS3 is in different situation than PS2.  Living here, FF will die about as soon as Mario, Pokemon, and Dragon Quest will die.

I'm going with answer 3.  America will be 500k-1m more on 360.  Europe will probably be 500k more on PS3.  Japan will be 1.5 mil to 2.5 million.  If it does port to 360 eventually in Japan, I don't see more than 200k for a late port.