This question - although asking about an on-topic work of sci-fi, the question is purely based on a real world question. Should this question be closed as off topic for seeking "Scientific Explanations", or should it be deemed on topic due to the work it's about?
The question here is "How long would the astronauts on the ISS have survived? And what would they have died from?" which seems to be asking from an out-of-universe perspective. That makes it off-topic since we only deal with fictional universes.
The issue of astronaut survival sounds exactly the sort of thing that Space:SE deal with, so it's worth prodding the user in that direction with a comment, albeit their question isn't migration-worthy.
Had they asked "How long did the astronauts on the ISS survive? And what did they die from?", that would be perfectly acceptable.