My nubians give about 2 pints per milking, per goat. I milk them twice a day. One is a first time freshener and the other is a 2 time freshener. The more freshenings (have kids) they have the more milk they will produce. My first time freshener gives as much as my 2 timer, but she is also out show lines that breed for milk production ability as well. While my other girl is just a grade Nubian, who came to me in poor condition. However under vet care and a good feed program she is 100% better and producing well.
It really depends on a lot of factors on how much milk you are going to get. Feed, bloodlines, condition etc, etc.