There really isn't much to gauge. If you win and schedule well in D1A, you draw over 40K. In New Orleans, that gets to 45K-50K faster than anywhere else.
I hate to be Debbie Downer JJ but you spout this line regularly. Tulane has never, ever, not even once, drawn a crowd of over 45K when the other team didn't bring 20K of their own fans.
You are correct, but...
Tulane has also been a very inconsistent winner, at best, when there haven't been long streaks of losing, which has been most of the time.
The closest that I can recall seeing to such a phenomenon was in the late 1970's - early 1980's.
I do believe strongly that in order to really test the theory that people would respond to seeing Tulane have success that there needs to be around 3-5 years of consistent on-field success, including some wins against well-regarded opposition -- and that hasn't happened since the aforementioned time period.
45,000 does seem like a stretch, though...but I also believe strongly that if you aren't drawing 30 to 35,000 game after game and then 35 to 40,000 at least some of the time your status as "big time" Div. 1 FBS is pretty tenuous. This is the real key issue. You either move forward and grow and have the program going places or else you slip back -- and in Tulane's case there isn't room for a whole lot more backward slippage without falling into the ranks of a lower classification.
Tulane, therefore, needs to really get after it and vastly expand the regular following and general interest level -- and then it also seems like the window of opportunity to move out and up is closing quickly given the number of programs that have already passed Tulane by.
Nonetheless there's this plan to move into a definitively smaller venue.
How are they really going to be able to do that and at the same time do what's genuinely needed in terms of vastly expanding the regular following? They can't. If they really want to have this new and much smaller stadium they might as well not even try to build a 30,000 capacity stadium. It would be a waste, and a 15,000 capacity facility will probably be quite sufficient.
Tulane sports: small football stadium, very small basketball arena, w̶i̶n̶n̶i̶n̶g̶ ̶p̶r̶o̶g̶r̶a̶m̶s̶, h̶o̶n̶e̶s̶t̶y̶ ̶a̶n̶d̶ ̶a̶c̶c̶o̶u̶n̶t̶a̶b̶i̶l̶i̶t̶y̶ , but, hey, now there's tailgating.