I'd peg him about 450 to 550...it's hard to tell.
This is what 1000 lbs looks like
And he would be 200 lbs heavier, in only 2 years.
Granted, he's probably taller than the man in the picture.
It would be very hard to do.
Imagine, that for every day he's "just" eating 5500 calories, he would then have to compensate with a day of 11500 calories.
And all of this on the assumption that his daily caloric expandure is 2500. If it is around 4000, which may be likely due to his body mass, he would have to consume 10 500 calories a day to get to 1200 lbs inside 2 years.
Could he do it?
Perhaps if he would frequent all you can eat buffets, et al.
But it's a slim shot (no pun intended).