If a domesticated dog, such as a pekingese, was placed in the wild as a puppy, would it be able to survive?

Probably not, but in some circumstances it would be able to. It also depends how much care they need in a home, and how much of that care can they do without. :) Yes, dogs can easily revert to being wild though, if you mean 'wild' charecter- biting, growling, fitting, etc.

It's doubtful that any domesticated dog and especially a puppy can survive in the wild. They may be able to manage for a short time, but they would succumb to predators, disease, foul weather, inability to hunt. Dogs could and do manage in urban areas but there are other hazards there such as traffic. Dogs in a pack do better at survival and do revert to wildness.