Fittipaldi, the grandson of two-time world champion Emerson Fittipaldi, is currently part of the Red Bull junior stable, racing for Rodin Carlin in Formula 2.
The Brazilian won his first race in the category at Spa-Francorchamps but admitted that he had no idea of Horner's plans for the academy setup.
"It's very competitive between us," Fittipaldi said to The Mirror. "At the end of the day, all six of us, the Red Bull drivers who are in Formula 2, we all have the same dream and goal.
“It's very competitive, but competitive is good. It pushes me personally to work harder and to try to improve myself every single day. It's healthy to have this type of competition.
"I haven't actually seen that (Horner’s admission that the RB junior team could see some drivers axed). I’m just focused on doing my job in my Formula 2 season and securing great results until the end of the season."
Fittipaldi is currently seventh in the Formula 2 standings as Sauber junior Theo Pourchaire leads the way from Mercedes youngster Frederik Vesti.
Ayumu Iwasa, who is third in the standings, is the best of the six Red Bull juniors.