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.