should be have. next time you can check on dictionary if you have any questions on any English words. it's useful and you'll definitely learn a lot from it.
buffet noun /ˈbʊf.eɪ//bəˈfeɪ/ n [C]
• a meal where people serve themselves different types of usually cold food
Are you having a sit-down meal or a buffet at the wedding?
• UK a restaurant in a station, where food and drinks can be bought and eaten