The 20-year-old forward has made just three senior appearances for the Cottagers, forcing him to seek regular game time at Wycombe Wanderers, Watford and Brentford.
Trotta has returned to Griffin Park for a second loan spell this season, and Jol hopes the Italian will show that he has a long-term future at Craven Cottage.
He said in the Fulham Chronicle: "For a player like Trotta, it's not easy to break into the first team.
"Trotta scored nine or 10 goals but in a lower league at Brentford, which is good.
"Hopefully for him he can score more goals now and step up a gear. Then maybe he can play for Fulham in the next couple of years."
Trotta's return to Brentford has not been universally well received by Bees supporters - after a missed penalty cost them promotion on the final day of last season - but Jol believes they should be welcoming the striker back with open arms.
He added: "Trotta is a goal machine. I think they should be very happy to get a player like him back.
"I wouldn't say he is the finished article, because he's not, but he gets around the box and can score goals.
"He has the right mentality, otherwise he wouldn't have gone there. He would probably have gone to another club because there were more options for him."