All Bayern Munich gave is now the Champions League and if they lose this tournament Tuchel can be even under more pressure and I guess he will do anything to not lose the match against Arsenal.
The Bundesliga title is already lost for Tuche and his players, he even said that in the conference after the game they had against Dortmund. They are going to now have a hard game against Arsenal, while Arsenal is in the good form and I think with the current situation of both teams, Arsenal can easily beat Bayern Munich.
Doing anything to probably still stay in the league isn't the problem but been able to maintain the form till the end and probably getting to win the trophy is what matters the most, Bayern Munich is still yet to really have what it takes to win the champions league this season, they will most definitely not be able to win the champions league and I wouldn't want to consider it fair enough if he's actually been judged by it.
I'm really optimistic about Bayern Munich actually, because I think since this is more like all that's left for them this season, giving their all is what they would want to do in the champions league this time because they are not going to in anyway really have hopes on other games as this is more likely to be their best bet at this point and knowing that Arsenal does better at the premier league then the champions league, Bayern could see that as an advantage to be well utilized and make sure to win as it's very possible Arsenal get to loose to Bayern Munich.
The fact that Arsenal actually faced Manchester city who is usually seen as a tough team and didn't get a loss from them for me isn't a reason to think that they can aswell get to be able to still beat Bayern or probably hold them to a draw too, I think what's more applicable is in the fact that Arsenal just like yesterday would want to be too careful so they get a draw here and probably later they could win and get ahead but I don't see Bayern playing in such a way.