Richarlison scored five goals in his first 13 Watford games but hasn't found the net since registering in the 2-0 defeat of West Ham in November.
“He's working a lot and trying to do better day-by-day. In the last games he's not finding his best performances," Gracia said.
“I think the next game or in the future, I'm sure he will do better."
Gracia added: “I don't know [if he is happy]. That question is for him. I'm sure he will be more happy if he scores a goal in the next game, or if he plays for 90 minutes, not just for 55 minutes."