It’s mentioned in a short comment in Solo: A Star Wars Story that Aurra Sing was killed by Tobias Beckett. He was doing a job for the Crimson Dawn crime syndicate, and he had an encounter with Sing. They battled, and it ended with Beckett pushing Sing off a ledge. Dryden Vos, the public leader of the Crimson Dawn, found out about it and paid Beckett extra for killing her. As this was just a brief comment in the movie and many Star Wars characters have fallen off ledges and lived before, we can’t be one hundred percent certain that she is dead. However, she is presumed to be dead for now.