I think the indications are that Mike survives -- Finn Wolfhard made the statement that he was the very last actor filmed before they wrapped....while they don't necessarily film everything in order, that is some indication that Finn's character (Mike) is there at the end.

Also, there was a released still of Mike and Hopper sitting talking together. Hopper was wearing the chief of police uniform. It had the feel and look of being an epilogue scene...