How Long Did The Dinosaurs Actually Survive After The Asteroid?

Well, some of them are around today. We call them birds.

The larger dinosaurs are hardsr to determine because fossilization doesn't get as precise as days or even hundreds of years. When the asteroid hit, the damage was global but even the largest dinosaurs had survived hundreds of milliions of years as megafauna, so there were likely to be pockets of survivors who got lucky enough to rough it out for a while. Something I saw recently was talking millions of years for a few large species, but without vast numbers they would eventually lose out to a lack of diversity and competing pressure from mammals and other animals that were more successful in the new conditions.

So anything remotely close the the blast probably died in the blast. Going from the blast to the ppposite side of the world smaller animals that could scavenge would have increasing odds of survival and there might be some lucky large ones that were able to find food sources that weren't completely wrecked. But small pockets of large animals have a hard time sustaining their numbers when food sources are not plentiful.