Galatasaray is not a team that can defeat Bayern Munich, if you analyse the both team Bayern Munich had more experience when it comes to Champions league, and their coach is also an experienced coach that has won the Champions League even before he came to Bayern Munich. Bayern Munich had better squad than what Galatasaray has, so I don't think Bayern Munich playing with Galatasaray will be a difficult game. Bayern Munich performance is still solid and it won't be easy or possible for Galatasaray to take advantage of them .
I wouldn't think it would be easy for any team to win in the Champions League even though the team strength is very different between Bayern Munich and Galatasaray. In terms of experience and strength of the squads of these two teams, Galatasaray is not better than Bayern Munich, but I think that there won't be too many wins for Bayern Munich in this match because any team will give all their abilities when competing in the Champions League.