No. 8 is living in Chicago and using her powers (which are different from Eleven's powers) to commit crimes and punish those who hurt the kids at Brenner's lab. Eleven joins them for a while, but when she finds out her friends back in Hawkins are in trouble, she leaves Eight and returns home. We do wonder if Eight is going to reappear in season three . . . or if there are other kids out there who we'll get to see.