"survive" is meaningless. Survival stories are either about reaching a loved one, a sanctuary, or exacting revenge. In The Road they are trying to get somewhere. In Fury Road it's The Green Place, and once they Spoiler: what happens then discover it no longer exists, the goal changes to creating their own sanctuary by taking the citadel . In Apocalypto, he is trying to make it back to his wife. In The Revenant, the first goal is to make it back to the outpost. Almost all survival stories have a physical goal the character is trying to reach, and the survival part is about trying to stay alive long enough to get there.
There's always still a goal if the characters are aware of the threat. In many horrors the characters are killed of while oblivious to the threat until finally the final girl figures it out. Then it's usually a case of get out to a specific location, OR eliminate the threat. In GOOD horror films simply trying to survive doesn't figure on it's own. You need to add a goal, like find an escape or eliminate the threat. Both are objectives with a defined outcome.
I get your point, and you're right, in that every action is motivated by a goal, immediate or long-term. In a lot of horror and survival thrillers though, killing the monster or escaping the murder house, so to speak, is just a means to an end, survival. Often revenge enters in, and that becomes a goal, but think Jurassic Park. The end goal is just to get out alive. They have tasks they must accomplish in order to do so, but no character motivations or emotions involving the threat they face (other than abject terror, of course.) They have no designs on revenge or hope for catharsis. They just don't want to die. Escaping is the means by which they achieve that goal.
I'm not really sure what genre this book would be yet. Is it Fantasy? Dystopian? Both? Of all the survival themed movies I've watched so far, everything the characters did was to escapes their current situation so they didn't die. To survive seems to be a natural instinct in all living things. So do you really need motivation beyond that? Like family, friends etc. I've read books where the book of the book was to show our bare instincts and our animal side, these characters had little motivation other than to live out some disaster.
