Okaka's Watford career looked to be all but over after it was revealed he was being allowed to look for a new club and had been absent from training.
"All three players are available and I am sure they will score many goals for the rest of the season. I trust in them," Gracia said.
"Troy is perfect, Okaka also and Andre Gray as well.
"I am very happy with all the players, but the strikers as well. The players who didn't play all the games, but their attitude is very important off the pitch as well."