If we're going to do that then nobody is purely anything because of possible match ups a makings in the past. Sorry, not sorry.
umm. This is Naruto manga, where like almost all clans keep it in the clan. Can't say 50/50 because Naruto have nearly no noticeable trait of uzumaki clan. All we know that he have a strong life force. He didn't get the red hair or healing power or chakra chain or anything that would easily point out that he is from the uzumaki clan.
5th hokage, Madara said she is from the senji clan due to her raw strength. Didn't see anything about her good enough to say she is from the Uzumaki clan.
The way that most people should look at it is if the character display abilities or look like they belong to "X" clan, they're from that clan.
The only reason I can see Naruto being from the uzumaki clan is his abilities to be a perfect jinchuuriki. Other then that, he is a half breed.
So really at the moment, Bolt is from the senji clan while his sister is from the hyuga.