Their financial instruments are so byzantine and dynamic that probably only one of their quants could tell you. It's probably less than could be hoped, given the level of corruption inherent to the system. Remember that literal crime is profitable even when you get caught, in Wall Street.
When I think they could just use that money to buy actual GME shares I realize they have probably shorted the float way too many times for that to provide them a reasonable way out.
Daily short vol * share price * borrow rate that day, accumulated over time.. I feel like that's the gist of it, but also like it's missing something wildly significant.