Revenues not best metric, neither are data centers
Total revenues are not a very useful measure of skill or potential longevity in the cloud market unless you're a pure play public cloud service. Which AWS is. Then they become a form of marketplace feedback. Revenues when used in connection with Microsoft are a more debatable measure, as is the number of "Azure data centers." How much of any given data center dispenses cloud infrastructure services, as AWS' do? Some part of the Azure data center is devoted to Bing searches, Dynamics CRM, Office 365, even possibly XBox playing. So it's difficult to say what either the data center number or the revenue nuimber indicates for Azure. Forrester estimated Azure revenues at $1-2 billion. AWS cited as having "more than $6 billion" in 2015.