I doubt anyone survived that was not on the Ark. The Bible is pretty clear that everything that "all flesh died that moved on the earth," listing birds, cattle, beasts, every creeping thing, and every man, and it even emphasizes "all in whose nostrils was the breath of the spirit of life, all that was on the dry land, died. So He destroyed all living things which were on the face of the ground: both man and cattle, creeping thing and bird of the air. They were destroyed from the earth. Only Noah and those who were with him in the ark remained alive."
The Bible is clear, but even so, there's literally no possible way that anyone could swim for well over 150 days nonstop without food or clean water in the freezing cold waters of the Flood, and that's ignoring the likelihood that they would have been eaten by sea creatures that were NOT destroyed in the Flood. Remember, the only creatures destroyed were man and beasts on the surface of the earth and birds. It says nothing about sea creatures.
No, the only humans to survive the Flood was Noah, his wife, his three sons, and the three women who were the wives of those sons. No one else could have.