He's 99.9% certain to stay at Dortmund for another year, he even came out and said himself that he respects the contract, I think any reports to the contrary are just English media being English media.
I don't really see him joining Bayern:
Haaland himself seems to be planning at least one stop in Spain and England, it doesn't make much sense to sign for another 4-5 years with Bayern first, when he's already had a couple of good years in Bundesliga and won a trophy, even if it's only the lesser of the two.
And from Bayern's perspective it doesn't make much sense either: Lewandowski is in the form of his life, still significantly better than Haaland, and going by photos he seems to be a model athlete that could go on for another couple of years. Are Bayern just going to send him away, for a player that already has his next step in mind the moment he signs? And what about the money? The Haalands and Raiola know exactly how valuable the boy is and they don't seem to hesitate in taking their share. Even if his release clause is as "low" as €75m (which is still about Bayern's record signing), they will demand the difference to his actual market value in wages and signing fees - and some clubs are going to pay that, just like with Alaba. He's going to be a proper galactico signing and Bayern have never done these.