I may be wrong but I think naruto is a distant relative of the sage of the six paths,and itachi some how shared his occular jutsu with naruto so that when combined with the kyubis powers he would be able to battle madara.
see must people think madara wins it becoz naruto has nothing in his sleeves as his father have.till now he is trying to create a new rasengan.while he cant use shadow clones as you know kisi has restricted him in his thunder-god mode or whatever.by the present status you can conclude why peoples votes are falling on madaras side .
whatever you think i expect that our unpredictable ninja will make out some way to defeat madara.