Am not going to conclude based on a team's current form or so cause some circumstances could make some team lose and give the current underdogs more chances of going into the semifinals, it maybe be injures, reduction of form by the general squad and so on, anyways if am to judge by the current form, I think both Liverpool and PSG are strong enough to play eachother but PSG would take it more seriously since their league is already secured.
The points they're using to gap the runners up on the table is too much therefore they'll channel all energy to the Champions league since it's the tournament they're yet to achieve in their history. Anyways an El Clasico match won't be bad but I think it would be more better for clubs from different leagues to play eachother in the finals
For team performance and the number of players who suffered injuries to each team will definitely affect because if that happens then the opportunity for any team to qualify for the semifinals will be a little more difficult. Liverpool are still on a positive track to compete for titles and vice versa with PSG which may for now they will fight hard to achieve better results, even though it is not easy to do because competition in the next round will definitely be far more difficult.
PSG can be far more focused because in Ligue 1 has no big challenges to get a trophy because the challenger is not so strong to pursue the points they have collected. But Liverpool will get a much more fierce competition so that their focus will certainly be divided into the two competitions. If the wrong step will make the opportunity disappear and the match will become more difficult because the victory in the first leg will determine and PSG is a little more benefited for playing at home.