Isaac Clarke's in-body experience is different than many of the others in this list, because the creature whose body he explores is frozen solid. Well, except for its "nerve clusters" that (for some unexplained reason) are still active--nerves that, when shot with a probe, cause a mini horde of creepy Necromorphs to come running.
Could he possibly survive? It's hard to say. It helps that the Nexus was in a frozen state, and because it's an alien creature, it very well could have a hollow cavity in its body. We'll give Isaac the benefit of the doubt on this one.