It's not the only GW datacenter planned [1]. AFAIK, a majority of these big datacenters are going to produce their power via natural gas turbines. I don't know of any that are actually planning on powering themselves via renewables or even nuclear power.
The sub 100MW data centers are mostly relying on the grid, but even a number of them plan on having natural gas turbines.
[1] https://cleanview.co/data-centers/us