Surveys are rarely reliable, because it's quite hard and time consuming to conduct surveys with reasonable margins of errors.
We won't have a clear picture of cloud computing until all major actors disclose the financial informations, for Microsoft, Azure, and not Azure + Office 365, and for Google, Google Cloud and not Google Cloud + Gsuite + whatever.
But if we are to believe what corporations tell us now, Azure and Google cloud and tencent grow almost 2x as fast as AWS, so AWS is slowly loosing its dominance, contrary to what this article implies.
Also it seems to me it is way too soon declaring victory in a field so young.
I remember the CIO of one of Europe' biggest company during a conference telling that they are doing projects concurrently on all major cloud services.
IMO, the service with the biggest chance to win eventually will be the most open and the one that can train the most developers the fastest. Training is probably where AWS shines, benefiting a lot from its first to market advantage.
Then there is the investment capability aspect, where Google and Microsoft lead Amazon by far. That's not a major advantage now, but it could be tomorrow, if/when most countries expect datacenters locally, or if a major technological advance would require costly datacenter upgrades.