I also expect Monaco to win because besides that, Monaco will also play at home and thus, it is only right that Monaco will not lose against Lille. Although it might only be a draw but I think it is also not bad at all although indeed, if for example Monaco gets a draw it is very possible for PSG to return to the top of the standings. But at least, PSG and Monaco will still have a close points gap and thus, their competition will continue and I hope it will happen throughout this season. If that happens, then of course the competition for the Ligue 1 trophy will be more interesting and it could be, maybe Monaco will break the Ligue 1 trophy streak this season, who knows.
Just before the expectations on Monaco is taken up already, we should know that Lille hasn't been doing any bad this season, as a matter of fact they at some point were a problem to PSG, tho they lost the game and Monaco isn't any better than PSG, so just so you don't get surprised, you should probably keep the expectations down as Monaco do not have very brilliant attack or finishers as much as PSG though their midfield is fair by my judgment but they need better finishing even if they are at the top of the table at the moment staying there long enough will be the next concern as they are just two points away from PSG. I still expect a win from Monaco even with all i have said about them already but Lille shouldn't be underestimated.