Marseille have done a good work so far. Especially after changing their manager they have been on the rise. We are witnessing its reflections in the Europa League as well. Their performance against Villarreal was really impressive especially in the home game. The Benfica matchup might be a little more difficult but I'm still favouring Marseille to advance. 
If Marseille make it to the semi finals I don't feel like they will see more than that phase.
Because their quite probable opponent would be Liverpool there and I wouldn't expect Marseille to eliminate Liverpool too. But at least there is good progress in their game since the latest manager change.
Perhaps Marseille will have a good chance against Benfica, I say this because I did not like the way Benfica played against Rangers, although I expected a more meaningful game from them.If Marseille make it to the semi finals I don't feel like they will see more than that phase.
Because their quite probable opponent would be Liverpool there and I wouldn't expect Marseille to eliminate Liverpool too. But at least there is good progress in their game since the latest manager change.Marseille played very well at home, I don’t remember the last time Villarreal lost by such a score, but in the return match they were very close to winning back, but instead Kloss took that hope away from them in extra time, and on 94 minute scored a goal. But if we evaluate the teams’ chances globally, then it is not so important who can win, because in the semi-finals they will have to play with Liverpool, and this will almost certainly mean their defeat, but of course they need to fight.