General rule of thumb for brown-egg layers is 4 square feet per bird inside the coop, nestbox at least a foot each way, one foot of perch space per bird, 10 square feet of run space per bird.
If the chickens come from a hatchery, that amount of space might be enough.
If they're coming from a breeder that selects for large size, you might need to scale things up.
I'm guessing here, but maybe 5-6 square feet per bird in the coop, nestbox 16-18 inches each direction, 16 to 18 inches of roost length each, 15 square feet each in the run.
More space is always good. I'm sure that double the "usual" space for coop and roost would be plenty, and of course there's no real upper limit on the run--if he's got a few spare acres, they might like access to it all! But realistically, the run could probably have 10 to 20 square feet per bird and be fine.