Depends on skills and the responsibility that they are hired for -- somebody that just "racks and stacks" generic hardware for faceless hosting company that has inconsequential web sites for low budget clients like PTAs and hobbyists might make $15/hr
At the other end of the spectrum someone working even as a third shift technician on operations desk for a high volume transactional web site like Amazon would be expected to not sit on their duff if an anomaly is detected but have the knowledge to diagnose issues that may be caused by failure of networking gear or potential malicious activity and initiate appropriate escalation. It is not uncommon for folks in such positions to take home a six figure salary...
Funny thing too is there never really a balance of people with either set of skills / experience -- more and more folks are looking for the cheapest hosting company and that means there are plenty of firms willing to cut corners and hire the people with no real skills beyond plugging in new servers. These firms will try to "slash costs" and "increase marketing" as dissatisfied clients leave and new ones need to be attracted.
At the other end of the spectrum for data center personnel every time some one gets let go for not keeping the "lights on" at google or Apple's online presence the managers demand that only someone with MORE experience and expertise is hired for the replacement...
Of course the shift of actual data centers out of "the Bay Area" and into place where energy, land, cost-of-living are all ORDERS OF MAGNITUDE lower means that people willing to live out in rural areas can have a much nicer lifestyle at a much more affordable salary to their employer
Lenoir, North Carolina ? Data Centers ? Google
Berkeley County, South Carolina ? Data Centers ? Google
Council Bluffs, Iowa ? Data Centers ? Google