Joyboy is a character from the ancient past of the One Piece world, who lived around 800 years ago. According to the story, Joyboy was a legendary figure who played a crucial role in the history of the world. He made a promise to the people of the Fish-Man Island, which he was unable to fulfill, and this promise is still relevant in the present storyline.
Luffy’s journey in One Piece is centered around his quest to become the Pirate King by finding the ultimate treasure, the One Piece, and surpassing all other pirates in the world. He is not related to Joyboy in any way, and his story has not intersected with Joyboy’s directly.
However, there are some theories and speculations among fans that Luffy may have some connection to Joyboy or that he may be a reincarnation of Joyboy. These theories are based on various clues and hints scattered throughout the series, such as Luffy’s ability to hear the voices of all things, which is a rare and mysterious ability that is believed to be linked to the ancient history of the world.
Still, these theories are not confirmed by the author, Eiichiro Oda, and are merely fan speculation. Therefore, I cannot provide an answer to your question as it is not supported by the official storyline of One Piece.