A back of the envelope approach to this is to ask how many people can a permaculture farmer feed?
And the answer is, "Not many" While permaculture can get outstanding efficiency in terms of calories per acre, it's abysmal at calories per man-year.
Consider: A Saskatchewan farmer typically can farm 16 sections (about 10 thousand acres) of land by himself. At 40 bushels per acre that's 400,000 bushels of wheat. Double that for barley, more yet for oats.
Ok. Not by himself. He's got a couple million dollars worth of equipment to help him.
Permaculture by it's nature uses the synergy that plants creating mutually supporting systems. This doesn't mechanize well.
There are two approaches that are complementary: One is espoused by Shepherd in "Restoration Agriculture" where he mixes tree crops and annuals in rows. Having long rows allows a large amount of mechanization. This does not use the full guild system of permaculture, but it's a lot more manageable.
The second approach is to use time: Longer crop rotations. 6, 8 year long crop rotations with several years in pasture to renew the soil. Shorter and more diverse livestock rotations. E.g. Cow-calf grazing for 2 weeks then steer grazing for 2 weeks. Then sheep, goats or pigs, then chickens or turkeys. (Shepherd is not clear on what to do about coyotes who want lambchops or short ribs for lunch)