There may be some differences in subtle meanings, or the situations in which each can be used. For example: "rich" can be used to describe how something tastes, while "affluent" cannot. For #1 and #2: The latter words (affluent and sever) sound more educated and formal, while the former (rich and cut) sound more casual. For #3: Really the only times that I've heard someone say "dignify" was in response to something offensive, childish, or otherwise unworthy of a response. You cannot use "revere" in this way. For example: Person A says something offensive (or asks an offensive question), and Person B says "I won't dignify that with a response".

rich = affluent cut = sever can be interchangeable but sever means more than cut. Sever is usually applied when speaking of separating something into two or taking off a piece. The man severed his finger. He severed off a piece of meat to taste. To sever is to cut but to cut is not always to sever. revere means to feel deep respect or admiration for (something). An example of revere: "She revered her grandmother for all she accomplished in her life." Dignify is to make (something) seem worthy and impressive. "the Americans had dignified their departure with a ceremony" synonyms: ennoble, enhance, distinguish, add distinction to, honor, grace, exalt, magnify, glorify, elevate "shall we dignify their arrival with some music?" give an impressive name to (someone or something that one considers worthless). "dumps are increasingly dignified as landfills" Revere and Dignify are not synonymous