At this time Peter Cullen has voiced Optimus Prime for 133 episodes over the course of G1, Prime, and Rescue Bots. While Gary Chalk has a total of 153 episode as Optimus Prime from Armada, Energon, and Cybertron. So actually Gary Chalk has voiced Optimus Prime more episode then Peter Cullen. Although Peter Cullen has voiced Optimus Prime in four about to be five movies and several video games. So the question is will Peter Cullen get another 20+ episode in as Optimus Prime? I am unsure it all depends of how much of a role he will play in the show. Also he has at least one more episode in Rescue Bots coming. Also not counting G1 season 5, G2, and Beast Wars/Machines.