A lot of this depends on the soil quality, slopes, water availability, and sunlight availability.

For this region (northern Michigan), I think the ideal plot of land would have a gently south facing slope, without much shade from trees further south, with a shallow water table easy to access with a DIY Sandpoint well, and loamy soil. Heavily wooded near the road for privacy.

Also, it depends on what is grown on it. Most studies you'll find about "how many people can an acre feed" will probably be based on conventional farming methods using commodity crops that are very inefficient on a small scale. (E.g, the least efficient usage of land on a small scale would probably be to grow grain to feed beef cattle.)

More efficient would be something that supports a diverse, mostly plant based diet with a small amount of chicken meat and eggs, just enough to meet basic protein needs. Substitute a rabbit hutch or a fish pond if you want. And obviously, any wildlife you manage to hunt.

The best survival (annual) crops are things that will give higher calories like potatoes, sweet potatoes, squash, beans and corn (both Sweet corn and Field corn for cornmeal) and the best (perennial) survival crops are nut and fruit trees. That covers protein and calories, but for nutrients and vitamins, leafy green annuals and dark berry bush perennials are best.

But the real determining factor in how much food a given piece of land can produce depends on how much labor is available. If you put more time and attention into maximizing a small piece of land, you can grow more food than someone who is putting minimal time and effort into a larger piece of land. There is a saying "the best fertilizer is the gardener's shadow" which means if the Gardners are active and out there, keeping on top of things and looking for every nook and cranny to put new plants, the garden will grow better.

With good design, a one acre garden with chickens could feed multiple people.