It really depends on where you work. Historians usually get jobs as professors, curators, collections managers, museum education conservators, publishing companies, archivists, government agencies, and historical preservations.
Historians who work as professors for private or public institutions make around $80k and associate professors make close to $60k, while new professors have to get their feet wet with around $50k.
If you work for the federal government—for example, at the Department of the Air Force—you can make between $55k-$75k working at their museum, or nearly that much if you land a job working for the National Parks Service.
Curators, museum technicians and conservators make roughly $40k a year. There is no set salary for historians, but the more education you have the better your chances of finding a high paying job. If you even want to be in the conversation for a sought-after museum job, you'll have to have a master's degree. It will mean putting in more time at school, but when studying spans of time lasting thousands of years, what's another four, really?