PSG should be able to qualify against Aston Villa. If they could qualify playing Liverpool, I don't see Aston Villa as a challenge for them. I believe they should secure a win both home and away against this said team.
Although PSG has been able to hold Liverpool from qualifying for the next round in the Champions League this season, it does not mean that we should equate Aston Villa's condition with Liverpool when Aston Villa faces PSG in the quarter-finals of the UCL this time. Because the condition of the team's strength in the Champions League is always difficult to predict, especially after the break in the last few days, there must be more changes that each team gets when they return to a big competition like the UCL. So PSG must remain vigilant against Aston Villa even though today PSG won big in Ligue1 at their opponent's home.
It can be assumed that PSG will find it easier to beat Aston Villa than Liverpool. But I agree that PSG should not be careless and underestimate their opponents, every team that makes it to the quarter-finals has something special. Unai Emery also has a pretty good squad depth although not as luxurious as PSG squad depth, the Premier League representatives have the potential to make a surprise like when they beat Bayern Munich in the League Phase.
A big win over Saint-Etienne shows that PSG are still in their best form after the International break, overall for the domestic competition I think there is nothing for them to worry about anymore. PSG only need one more win to lock the Ligue 1 trophy, and I think they will also win the French Cup. So automatically in the future Luis Enrique can focus fully on the Champions League.