Scientific polling post-debate shows most people thought Biden won. Here is a link to one from Ipsos and 538:
https://projects.fivethirtyeight.com...n-debate-poll/
With that said, unlikely this moved the needle one way or the other in terms of the election. Which I suppose makes this a win for Biden given he has had a more or less stable 5-8 point lead since the summer.
For what that’s worth the leader in the polls this close to an election has gone on to win the popular vote in every election since 1976, though they did lose the electoral college twice (2000 and 2016).