official number was announced as 65k but I would estimate it to be more like 55k....
I don't know man, it looked pretty darn full except for the upper deck (which had scatterings of people in it, but was largely empty).
Down in the lower two-thirds of the stadium, the only gaps I could see were (1) in the S-T-U-V sections that were roped off for some special group (family of the players and coaches? visiting recruits? student body? all the above?), which was about 2/3 full at the high point, and (2) one small area way up at the top on the end closest to the Hill. There was a triangle-shaped area of about 200 seats that was like 1/3 full.
Otherwise, it was decently packed, say at least 85% for the lower bowl.
Someone once said (I can't verify this) that the lower bowl = 70,000. If that's true, and we had 85% or better of the lower bowl (59,500+, call it 60,000) and 10% of the upper bowl (3,200 or so), that equals about 63,000-64,000.
In short, I think the official number seems pretty accurate and very believable. Just based on where I was sitting in section C, and what I could see.