Vikings season 6B revealed Floki was alive and well, and there are good reasons for him not to have been killed in the cave.

Is floki alive in season 6?

Floki was eventually able to reunite with his friends when Ubbe and Torvi (Georgia Hirst) were shocked to find he had arrived in the New World first. While some viewers felt his absence throughout the rest of season six, Hirst admitted he was far too significant not to bring back for one more appearance.

Does floki come back in Season 6 of Vikings?

When Ubbe asks why he left Iceland, Floki replies with, “I left when the sadness became too much. I was overwhelmed. ... Fans will be glad to know that Floki has returned for the final season of Vikings, and he's been reunited with a son of Ragnar.