Can hiv survive the acids in your stomach or digestive system?

Probably not: The concern is that oral sex admits the virus through the tonsils or other head-and-neck lymphoid tissue. Epidemiology shows it's not very efficient; women just aren't getting it from women this way, and catching it from a man seems difficult. Safe stuff (barrier protection, monogamy with someone hiv-negative) is still by far your best choice.