With my best attempts I arrived at the following translation:
There are considerable signs of Exos outside the room too…but most of them(?) have escaped death.
Whilst the "escaping death" part makes sense in the context (context here is an "エクソ" waking up in a strange hospital room after a battle and saying the above sentence whilst looking around the unfamiliar room) I don't understand the need for the conjunction (が) the way I interpreted the sentence in my head.
I mean, to me if the sentence was actually "There are considerable signs of Exos outside the room too… most of them have escaped death." With no が/but it would make sense to me.