Recently, during the finale of the Arrowverse crossover "Crisis on Infinite Earths", Oliver Queen was shown dying while saving the world from the Anti-Monitor. So is he really dead or he is still alive somewhere?
The Monitor took Felicity from 2040 to see Oliver and warns her there is no coming back. Felicity comments that she didn't expect the afterlife to look so much like Oliver's old office, and Oliver says it's a long story but he has all the time in the world to tell it to her.
They are effectively both dead and in the show/universe equivalent of Heaven.