Drogba, who scored the winning penalty in Chelsea's Champions League final victory over Bayern Munich last weekend, is widely expected to move to China after revealing he will leave Stamford Bridge.
The Ivory Coast forward has a prolific record at Chelsea, unlike £50million man Torres, but Gourlay has backed the 28-year-old Spaniard to get back among the goals regularly next season.
"We've got Fernando Torres. And Fernando Torres is the man that we will go forward with and Fernando Torres will score us the goals," Gourlay said.
"Have no doubt that Fernando Torres is a world-class centre-forward and Fernando Torres will score goals for Chelsea. I'm not worried at all. We've just won the Champions League and Fernando Torres played his part in that.
"It's not all about goals. It's not just about the individual scoring goals, his teamwork - he is a very, very important player."
Torres was critical of the club for not giving him enough chances this season, but if a new striker is signed in the summer Gourlay revealed it would be to support the former Atletico Madrid and Liverpool player, and not to replace him.
"We may have two big-name centre-forwards scoring 25-30 goals for us next season and maybe then we will improve on our sixth position in the league," he said.
Chelsea have reportedly registered an interest with Lille for their Belgium international midfielder Eden Hazard, joining Manchester United and Premier League champions Manchester City in the hunt for his signature.
Although Gourlay would not confirm the speculation, he was quick to point out he would not get involved in bidding wars with rival clubs.
He said: "There are a number of targets out there and I'm not going to say whether he is one of not.
"We will identify the targets...and will make every effort possible to make sure they come to Chelsea.
"Hopefully if anyone wants to go to a club and win championships and medals then we have demonstrated we can do that and have done that in the past and we have every intention of continuing along those lines in the future.
"If you remember at the end of last season I said I would not get into player bartering with any other club domestically. And that's still the view because you can't.
"At the end of the day we have financial fair play and other football clubs are in the same situation as us. You have to meet certain criteria and while it differs for some European clubs on the basis of how they generate their revenues, certainly the domestic teams are all audited the same way.
"We know what the challenges are - we will have a valuation on a player and if we can't make that work we will drop out."
Of the young players already on the books at Chelsea, Gourlay confirmed it was likely striker Romelu Lukaku and goalkeeper Thibaut Courtois would travel with the squad on the pre-season tour of America before decisions are made on whether they remain at Stamford Bridge or are loaned out to gain first-team experience.