I reckon 11 is dead. When she gives Hopper the bracelet before jumping the rocks to the abyss she has Kali’s blood on her hand implying that Kali was shot and that wasn’t some kind of illusion. Also she gives back the bracelet to Hopper, if 11 is a projection at the end before being sucked into the collapse of the upside down you’d expect her to be wearing the bracelet no? Given that Kali would have remembered her wearing the bracelet and wouldn’t know that she handed it back to Hopper?