I don't know for sure, but I'd guess MS Office makes up most of the revenue for their cloud offerings. Honestly I think their cloud is mostly a service to push MS Office harder, and they seem to be doing quite well for that.
My point is every cloud vendor needs to break up revenue by IaaS, SaaS, and PaaS. Each one looks strong and bad across segments and hence such a breakup will never happen. But saying AWS or MSFT is #1 misses the dominant segment where they are leading, hides where they are struggling, and gives an incorrect impression.