The winger has returned early from a serious ankle injury, which many believed would keep him out for the season.
Amad made his comeback as a late sub in their Europa League semifinal first-leg win at Athletic Bilbao on Thursday night.
Amorim, ahead of facing Brentford on Sunday, said: “Yeah, it was really tough on us because in that moment, he was the player that created all the situations and then pass a little bit for Bruno (Fernandes).
"So to lose a player like that in that moment with a lot of games was really hard for us and especially for Amad, because he was leaving at a good moment. But now he's returning.
"You can feel that he's not so explosive in the moment, but he's a player with a characteristic left foot, different from (Alejandro) Garnacho, that has one against one.
"And we don't have many players, to do that. So it's massive for us. And he's one more option to play.”