On the winners bracket side the final match the winner of winners bracket must win once and the winner of losers bracket must win twice. How many games does the winner of the winners bracket have to win and the winner of the losers bracket have to win?
How many _games_? You can give a minimum, but it can vary.
e.g. if the event's matches are best 3 out of 5, the winner of the winner's bracket has to win one 3 out of 5 match before the winner of the loser's bracket wins 2 matches.
At a minimum, they need to win 3 games (say, the first 3 games to win the match 3-0). But they could lose two matches 3-2 3-2, and they've won 4 games but they've lost the 2 matches.