Galatasary will not win against Bayern because they have a solid team and most importantly Bayern’s keeper knows how to keep unlike Onana. Furthermore they can try and frustrate Bayern to earn an point but it would be a risky strategy hence I feel that they should take their chances and attack Bayern and hope for an miracle.
Galatasaray will definitely try to play attacking football, because playing defensively against Bayern is almost a death sentence. But Galatasaray has a bad defense, they concede a lot of goals and even despite their desire to play attacking football, Bayern will most likely score more goals against them. Galatasaray has a very long unbeaten streak, but all streaks must end at some point, Bayern will help them with this.