Yes, the performance of Motta as Bologna's head coach this season in the Serie A League will not determine if he will do well at Juventus next season. Juventus is a big club in the Italian Serie A League and more difficult to manage than Bologna because you are expected to win your matches, and if you fail to win silverware as Juventus head coach, you will likely lose your job. Managing Juventus will be difficult for Motta; the pressure to win matches will be high on him, and if he doesn't know the right thing to do, he might use the wrong tactics that give him bad results at Juventus.
I think Motta has seen Juventus before and read how he can play Juventus well, it cannot be denied that Juventus have quite slick and good players, even better than Bologna, from what I have seen so far, it's just that last season Bologna was quite consistent and Juventus lost its consistency so he was not very good.
We don't know if Motta can have a better performance after Bologna, we don't know about that, but one belief that Juventus owners have is that Motta is a great person and they really believe in Motta's ability for one season yesterday, so if Motta doesn't have the ability, it's impossible to be hired at Juventus.
The final result is yet to be seen, we can only guess at this time, but the hope is always there to perform better at Juventus because they have suffered for a long time, I think maybe if Motta performs worse than Allegri he just needs time to adapt and get to know how Juventus can win the goal.