No risk of hypothermia here so possible if he had access to drinking water. If no drinking water then lies or misreporting for sure.
Just speculation but was the oil tank a jerry tank with water inside? Or did he have a jerry can of water with him.
Or as other posters have said, just 300 meters from a big inhabited island, why did he not just swim ashore?
Youtuber stunt perhaps.......I note that he was only 30 years old......