The appeal process won’t start until he is sentenced in July. The appeal won’t be decided until after the election.
So in theory, the conviction could tank his candidacy. But then months later his appeal is overturned, and the reason for his defeat in the election looks more and more like election interference - lost because of the conviction, only for the conviction to be over turned after the election, surely everyone sees that that’s not fair.
My prediction? Trump will lose support in the polls for a few weeks, but I expect him to rebound. Trump is lucky this trial didn’t take place in October.