Well, obviously the crusaders were strong enough to take a reasonably well-defended Constantinople, so they aren't a force to be taken lightly. The Ayyubids are in a critical phase of consolidation after several natural disasters and a civil war between Saladin's son al-Afdal & brother al-Adil, with the latter ultimately triumphing by 1202. Al-Adil himself (AKA Saphadin to the crusaders) was a capable ruler like his brother, though more inclined to peaceful ways - he was first and foremost a diplomat & administrator, not a conquering general (though IIRC he wasn't bad at warfare either), and historically worked to prevent an Ayyubid collapse after the chaos that marred the start of his reign.
So I'd say 50/50. Ayyubid Egypt hasn't recovered from their civil war, famine and quake since all that literally just happened right before the 1202 launch of the Fourth Crusade, but al-Adil is sure to at least give the crusaders a good fight. The crusaders have a sizable army, a mighty navy and competent, experienced leaders of their own (the Flemish brothers Baldwin and Henry who both historically became Latin Emperors, Boniface of Montferrat, and obviously Enrico Dandolo). Could definitely go either way - if the crusaders are to win, they could ironically loosely follow the steps of the RL Fourth Crusade against al-Adil, with al-Afdal filling a role similar to Alexios IV Angelos (a pretender tagging along with the crusaders under the promise of giving them peace, gold and generous land cessions if restored to the Egyptian throne, only to almost certainly die either at the hands of his 'allies' or Egyptians pissed off at his siding with the Christians).