I think the match between Real Madrid and Barcelona will be won by Real Madrid. Real Madrid is currently in the euphoria of winning, at least it will be very good for the morale of their players. Apart from that, this match is Real Madrid's home match, so it is clear that crowds will be a huge advantage for Real Madrid. Meanwhile, for Barcelona, the painful defeat to PSG clearly had quite an impact on their mentality, so playing away at Real Madrid's headquarters will clearly be quite a tough battle for them.
If Barcelona loses this match, then there is no longer any hope left for them this season.
The El Clasico match will still be fierce even though the two teams have different capital in the Champions League quarter final match, this meeting could reopen Barcelona opportunity to hunt for the La Liga trophy this season. Madrid certainly will not let this happen and Ancelotti will not underestimate Barcelona strength. Therefore, Madrid wants to ensure that the point difference that has been formed can be maintained until the end of the season. On paper, Madrid's chances of winning the match are higher, because they will also act as hosts.
On the other hand, Madrid position at the top of the standings is actually safe, and in my opinion would not be a problem if Madrid lost points in the EL Clasico match. Barcelona chances of winning La Liga are actually very slim, but Xavi must remain optimistic about maintaining his hopes and winning the El Clasico match. In the first half of the season Barcelona had to bend their knees before Madrid, we'll see if Barcelona can beat Madrid this time or both will play a draw.