Please don't drag up year old threads. If you have a question start a new thread or do a search.
Depending on how long you are leaving you are going to want to get someone to do water changes on your tank. If your tank is under 3 gallons it's going to need at least 2 water changes a week. While the person does water changes they can also feed your betta.
Bettas can go up to a month without food but it's not healthy for them. If your going away for like a week they'll be fine without food, anything longer than that and they'll need to have someone to come do a water change anyways.