How much do teachers with Ph.D earn?

It depends on the college, and the job. A community college in a rural area with a low budget might pay $40,000 (or less) to a new instructor, while an exclusive private college might pay someone else with a PhD in a rarer field or who has a higher administrative position six figures (or more). Here is a salary study, but again it differs by ranked schools, by the official titles, and so forth... but it might give you an idea of the average, if you have additional information:
http://chronicle.com/stats/aaup/aaupresults.php