So I know this is a bit older but so many of these answers are just wrong. Yes the four tails is a reference to Goku from Dragon Ball. He has four tails like the four star ball, he is giant ape like the great ape form, and his jinchūriki is named Roshi like Master Roshi. Now Goku is based on Sun Wukong and so is the four tails, but he was specifically based on Goku and not the original story. He does reference the original in ways that DBZ Goku does not, but he is still primarily based on him and not the original. Say someone invented the color blue (Sun Wukong), someone else sees blue and makes green (DBZ Goku) based on that, finally someone sees green and makes yellow (Naruto Goku) based on that. You can't really say yellow is based on blue in this situation. While yellow wouldn't exist without blue, there is no yellow in blue and it couldn't be made without first seeing the green that had blue and yellow in it. Something can be based on something that is based on something else without being based on the original. One Piece and specifically Luffy are inspired and partially based on Dragon Ball and Goku but you couldn't say that was based on the original really. Especially since Dragon Ball is, in the end, its own story and is capable of inspiring things on its own. While I'm sure the creator of Naruto knows the original Journey to the West, if he had never read it or heard of it he still could have been inspired by Dragon Ball without ever having known the original.