Can coffee give a person stomach ulcers?

For some people, yes: There are people with exquisite sensitivity to things that either are acidic or promote more acid flow in the stomach, and coffee (caffeine in particular, but also oils in the coffee itself) is certainly one of those, and they can be prone to stomach and duodenal ulcers, as well as reflux esophagitis and gastritis. Other people seem to have cast-iron stomachs and nothing bothers them.