The 19-year-old, who has impressed since arriving on Merseyside from Camp Nou during the summer on a season-long loan, has an option within the deal to remain at Goodison Park on loan for a further campaign.
"Gerard is such a special footballer," Martinez said in a press conference. "His talent is there for everyone to see. Gerard has adjusted to the British game.
"Whatever happens, I hope some of his best memories are at Everton. We will sit down with Barca at the end of the season [to discuss a possible second year loan]. Not one for now."
The Spaniard received plenty of plaudits for his performance against Arsenal last weekend, when he netted the equaliser in a 1-1 draw at the Emirates.