We do not know who place a bet for Biden, so we do not know who the winner is. If other members here place that bet and win, he can come out and tell us how much money he owns and hope that he can withdraw his win money. I think that will be a lot of money that he can win, but that will depend on how much money he bet on that event.
We might not know how much exactly they win or lose but we have a betting odds for that, and Biden was the favorites during the election, therefore winners only won lower than their bets which is less than 100%.
This is not exactly the betting odds as there are some movements to consider, but we can view this as an estimate.
https://www.actionnetwork.com/politics/2020-election-odds-presidential-race-donald-trump-joe-biden