We are going group of 6, how much can be approx per person?

Expect something between 60-70 per person.

With drinks (1-2 per person) probably $60 per person (including tip)

I agree with the $60 or so per person

Depends on what you are ordering. If it's food and drink, from $50 is okay! Drink alone, $20 will do if you ain't gonna drink much.