how does this compare to the depreciation cost of their datacenters?
The financials have a line below Net Income Line called "Reconciled depreciation" with about $16.7 billion. I do not know what that means (maybe this is how they get to the EBITDA metric) but maybe this is the metric you are looking for.
https://pbs.twimg.com/media/GxIeCe7bkAEwXju?format=jpg&name=...