
The main reason I believe she's alive is that we know Mike's theory that Kali had a change of heart is at least somewhat true. We saw that she was moved by Hopper's speech to El and put her gun down, which Mike didn't even see. I'm not fully convinced that the scenes we saw of Mike's story were reality though. She could be alive and we could still be seeing his imagination.
Kali would have had to not bleed out from the gunshot wound, have enough energy and concentration to pull off the illusion, survive the initial c4 blast and not lose concentration, survive the exotic matter explosion and not lose concentration, and then maintain the illusion through the inevitable collapse of the lab. That isn’t accounting for the fact that eleven would have had to bypass every soldier there while being bombarded with the sound machines. Plus how would Kali even know to do it?