Unfortunately, we don't know what happened to all the Beast Pirates. There are almost 20,000 people. Black Maria and her gang are the only ones where there is a high probability that they were burned alive because this fight was the only one where almost everything was surrounded by fire. This was long before Jinbe and Raizo put out the fire throughout the castle. Because Maria was unconscious, there was no way she could have survived unless someone saved her. If she doesn't show up again, we can assume she's dead.