None? There's like 12 jobs per datacenter and the revenue goes to the Valley, mostly. The utilities get some profit but I doubt that money stays very local either.
Data centers pay taxes don’t they? That money presumably goes into funding government services which would necessarily raise the local GDP
Places I know that are getting them are generally seeing big time pay (relatively that is) for construction work and then dozens to a hundred of ongoing jobs once the work is done. That doesn't sound like much but it's huge for many of these communities.