You do understand that Mito and Kushina are both of the Uzamaki clan which means they are related some what distantly. So yes Tsunade and Naruto are related distantly just as all Senju and Uzamaki's where from the start.
They are both descendants of the younger brother of the Rikudou Sage.
Wait why is this thread still here?
Because it highlights the rampent incest of the Narutoverse? or ummmm... argh i got nothing, close it