Well, in the official Naruto story, Naruto and Kakashi have a teacher - student relationship and there's no such family connection. But in the vast world of fanfiction, anything is possible. Maybe some fans got really creative and thought, 'Hey, what if Naruto was Kakashi's dad?' So they might have written a story like that. However, I haven't actually read one. It could be really interesting to see how they would justify such a relationship within the Naruto world, considering all the existing storylines and character traits.
There might be such a fanfiction out there. Fanfiction writers often come up with very creative and sometimes out - of - the - box ideas. But in the original Naruto story, this is completely against the established lore. In the original, Naruto is an orphan whose father was Minato Namikaze. Kakashi was his teacher. So if there is a 'naruto is kakashi's dad' fanfiction, it would be a very different and alternative take on the Naruto universe, reimagining relationships and backstories in a radical way.
I'm not sure if there is such a specific fanfiction. The Naruto series has a set official family structure where Naruto has his own parents, and Kakashi has his own backstory. However, in the world of fanfiction, all kinds of wild ideas can exist, but I haven't personally come across one where Naruto is Kakashi's dad.