First of all, in order to support football, you not only would need to fund the 85 football players, but the 85 scholarships that also have to be given to female athletes to offset the ones given to males. Second, pensions typically assume a 6% return, but most, if not all of the are in the process of crashing and burning, because they have been unable to return that much, and that's been in a bull market. What happens in a bear market? Third, OUPride is correct - the fun can only pay out perhaps 4% of it's assets per year, or it will shrink. Note, however, that if people continue to contribute to the fund, it could pay out more than 4% and still not shrink. Take these together, and I think $130m would be what you would need.
No, you don't have to fund the female sports the same way. You could endow the football scholarships and then continue to pay for the female sports with student fees. If Frank's friend Warren Buffet wants to give $50,000,000 to the football program there's nothing that requires him as a private donor to give an equal amount to women's sports. He might if he wanted to, but he doesn't have to. Title IX doesn't say anything about where the money has to come from for an equal number of scholarships, just that the numbers have to be equivalent.
University endowments are not pensions. The typically earned amount can be considerably greater than six percent. The problem with many pension funds is that they have been terribly mismanaged. I cite for example in Ohio the difference between the relatively well-managed OPERS system and fraud-ridden, mismanaged STRS system. Anyone remember the million dollar art objects in Columbus?