It seems to me on the contrary, Atlético’s chances of reaching the top 4 are falling due to the fact that they have a good position in the Champions League. If they can beat Dortmund, then on the way to the final one of the pair PSG - Barcelona will be waiting for them (this is much better than Real, Bayern, City or Arsenal as in the second branch to the final). Maybe it will turn out that they will give all their strength (due to motivation) in the Champions League and lose points in La Liga. I wouldn’t be surprised if they lose the head-to-head match to Athletic and worsen their situation.
That's not a reason in my opinion because even though the Atletico Madrid team will still fight for a top 4 position so that they can still get a ticket to the Champions League next season, if they hope to win the Champion League title this season I think it is very difficult.
In fact, teams that are focused on the European stage make the team's mentality and confidence better when facing matches in La Liga, especially if they have the same motivation.
So in my opinion Atletico Madrid's chances of finishing in the top 4 are still quite wide open, now Atletico Madrid is only 1 point different from the 4th ranked team and with 9 more matches left in this season their chances are very wide open.