Having been in some very serious situations, but not this specific one, all I can confidently say is there is no way to know in advance what we would actually do when a situation unfolds.
I live in a natural disaster prone area. I know people who have died in this kind of situation. I evacuated early, with my dogs and humans, so was never in a position where I could have the opportunity to find out what my exact reaction would be.
It's very likely, in this situation, that many people wouldn't save anyone as their own survival instinct kicks in, even if did have the time. Most people would instinctively save themselves, in spite of what they think they would do.
When I have been in situations where quick thinking and dire circumstances have existed, I'm pleased to say my instinctive reaction is always to auto-pilot into the mode of doing the right thing (which has never involved deciding between people or animals). I have saved someone's life before when everyone around me just froze or panicked.
But there is my final answer, based on experience and field of study, that none of us actually know what instincts would kick in and how we would react in that scenario until we have been there. People can say what they think they would do but they don't know.