I think how many goals will juventus make at this game is depend on Pescara strategy. I am sure Pescara will apply full defensive method unless the offensive one since Juventus is better then Pescara at everey lines. So, If Pescara used the defensive strategy then its hard for Juventus to make more than 3 goals. And if Pescara played openly in the hope they can win the game or at least get one point from this game, then the story will be very different.
I agree with you, we could see Juventus were struggling to score when played against Chievo Verona in last gameweek. At that match, Chievo Verona were using 5 defenders and I think they succeeded to make Juventus frustrated. Fortunately Pjanic saved Juventus by his free kick goal. I think if Pescara use same strategy with Chievo, Juventus would get a problem.