We drive that route on I-80 four or five times a year. It's no issue at all with fuel. I don't think there' any long stretch at all without fuel. Dan P mentioned the big towns, but there are plenty of other smaller towns and some tiny ones with gas stations. As killer_bob noted, I-70 definitely has a significantly long stretch with no services. But not I-80.
We also drive that stretch of I-80 a few times a year, it's a major trucking route, so gas stations are plentiful. Use GasBuddy.com to find the best prices in various towns.