how to determine the cutlery need for a restaurant?

Answer 1

That all depends on the type of restaurant. General rule of thumb is, the more upscale the restaurant, the more "upscale" the cutlery.

Things to consider:
Volume of usage: the cutlery must be able to hold up to the projected wear and tear.
Weight: A heavier weight utensil feels more "substantial" in your hands and lends itself to a feeling of "quality".
Design: Simple clean design or something more ornate?
Courses: The more courses offered at the restaurant ,the more types of cutlery needed.
Cost: The biggest limitation there is.

Something else to consider. The interior (decoration, design, furniture, ambiance, etc) of the restaurant is one thing. The food is another. Cutlery, glassware, and plateware is another. Remember, your guests will come into closer contact with the glasses, silverware, and plateware, more than anything else. The act of eating is the interaction the guest has with your facility. Skimp out in this area and it will be known.

Often these smaller details are overlooked when designing a restaurant, but they place a large part in the guest's overall experience within your establishment.

Answer 2

The kind of food you are serving, the area you are in and of course the cost.