Eyeballing it, that's like #8000 - 8500 calories.
I do believe the supplements, simply because he is comped those. I don't believe the diet as much, just last year he mentioned that it was mostly red meat, milk, and eggs that made up the bulk of his diet. I'm sure the calories fluctuate as well.
People have mentioned that he is much cleaner in diet than many Strongmen / Powerlifters.