It all depends on how large a project you have in mind. A large establishment will need waiters as well as a manager or supervisor – a responsible person who controls the smooth operation of the kitchen and the hall, who is ready to help in disputable situations and who is able to deal with a crisis quickly. Moreover, the supervisor or manager will be responsible for the cash register and payments to customers.
If we are talking about a very small café operating in fast food mode (i.e. with the task of serving food to visitors as quickly as possible, which is convenient to eat both sitting down and on the go), then at the beginning it is quite possible to get by with a minimum number of staff. The functions of manager, manager, cashier and waiter can all be performed by the same person. But remember that any employee needs a replacement, and preferably not one. Even a small coffee shop will require a minimum of two baristas who work a two-by-two schedule.
Regardless of whether you have an entire staff or just one person, it is important to organise the waiter-cashier space so that he can take orders quickly, send them to the kitchen and receive payment from customers.