A Chihuahua can have between 1 and 6 puppies in every litter. If this is her first litter it is likely to be fewer puppies. On average a Chihuahua litter size is 3 puppies. THe puppies will weight 2 1/2oz at birth and will weigh 7 oz after 4 weeks.
Chihuahuas are able to have between 1 and 4 pups, though it is far more likely for the chihuahua to only give birth to one or two. However, it really depends on the dog for whether or not you will get a large litter.