My pitt had pups 1 month ago she so thin how can I get her weight back or does this take awhile

Yes it does take a while but you can help her along a bit by giving her highest protein and energy content dog food possible. This can be accomplished by offering her puppy food (highest protein) until she gets her strength back up. For dogs that continue to lose weight, add one tablespoon of high fat material per cup of dog food; this can be vegetable oil.

She also probably needs to be wormed.