Kaguya was already stated to be superior to Madara.
Madara isn't even at JJ Hagoromo's level who is still inferior to her.
As you can see, some people actually believe he can beat her. Some say because of experience but that didn't help him against Naruto and Sasuke when he had one eye. That's probably because he has less than a day of experience with that kind of power. Then again, that probably doesn't matter at that point of the series where Naruto and Sasuke learned how to use their powers in less than a day as well and mastered their powers in 2 years or so despite there being no serious conflict for constant fighting.