I heard the same thing. I believe it was four years of a successful series and the actor was set for life. Given how unlikely it is to get that four-year show, I certainly wouldn’t bank on it...
Apparently, the trick is that if your show is around for 100 episodes they can syndicate it, at which point the dough just rolls in.
Of course that’s what Artie Lange from the Howard Stern Show said a few years ago to some actor whose show was about to hit the 100 episode threshold, and the actor agreed.
Actors in successful television series earn much less today. My accountant does television acting work and says that the salaries are way down. His gigs are typically small roles and does the work mostly as a hobby during the slow accounting months, but he says the big stars earn a fraction of what they did earlier.
"After you've been a major character in a successful series like 'Stargate SG-1' for 4 or 5 years -- let alone 10 years -- you never have to work again. Your children will never have to work. Your grandchildren will work only if they want to."