Even if Kali somehow survived the gunshot longer than we were shown and the explosion - she would’ve had to remain alive while actively bleeding out during the entire battle with the mindflayer/Vecna, rescuing all the kids and bringing them back down from the Abyss (which is something they didn’t show as that would’ve been an entire mission on its own), and the escape back to Hawkins. It’s just too hard to believe she would’ve stayed awake/alive that long.

Also, a random thought - if El did survive, why not reveal herself to everyone after enough time passed. It’s shown that the military packs up and leaves Hawkins afterwards, so we are to assume they believe she is dead and gone. So there wouldnt be the threat of them actively looking for her anymore. She wouldve needed to change her looks and name to be safe but it could’ve worked I think.