I'm not really sure whether he can lift Barcelona because I saw his inconsistency in coaching Munich. Because currently Barcelona is having a difficult time winning matches. Plus poor financial conditions.
It would be better for Tuchel to stay in Munich until he can prove that he can bring Munich to win lots of domestic and UCL trophies. Moreover, it should be easier now because he has Kane who really shows excellent qualities as a goal-hungry striker.
I also agree more if Tuchel wants to stay at Bayern Munich rather than leaving there for Barcelona, because Barcelona doesn't just need a great coach like Tuchel. But it also requires several great players in several lines to be able to improve its performance to be even better, because currently Barcelona's decline is increasingly visible. Meanwhile, Bayern Munich is still quite good with its performance this season and is even still a candidate for the Bundesliga title.