The question of survival is linked to the relative time Romilly spent awake on Endurance while waiting for the return of his colleagues. It is debated how realistic the gravitational time dilation was in the movie. The mass of the planet his colleagues visited would have to be massive enough to slow time for them while at the same time not crush their bodies. Simultaneously, the gravitational pull of the black hole in space would have to be enough to effectively cancel out the mass of the planet for Romilly so that the gravitational force was so negligible in comparison (relative) to the folks on the planet. The Endurance was likely hanging out at a Lagrange point in order to conserve fuel by sitting in a place with equal pull from the black hole and the planet. Metabolic processes, in theory, accelerate to full potential when gravity is not slowing things down, thus aging. While higher gravity slows everything down, even pure energy such as light, thus disputably, aging is slowed. The Endurance was likely stocked with nutrient precursors, components that could have been fed to bacteria in specialized reactors in order to produce proteins, carbohydrates, sugars, much like how industrial processes make vitamins such as B12 today. Using bacteria and photosynthetic processes will be the future of generating caloric supply, using basic building blocks like carbon, oxygen, nitrogen, hydrogen, light and other radiant forms of energy and specialized bacteria and cellular cultures. All of these components can be recycled and reused. Romilly's waste would have been recycled, fed to the bacteria, so to speak. With resources like these and cryogenic hibernation reducing metabolic function to near zero for extended periods of time, it would have not been so difficult for one person to survive.
