The restaurant manager, Steve Weng, told the paper he had no idea how the chemicals, some form of acid, had got into the children's drink.
Davis said: "How do you take your kids out and expect this to happen? We were supposed to be celebrating his birthday."
She said Richie already had cystic fibrosis and diabetes.
His father, Richard Zaragoza snr said: "He's been through a lot."
The restaurant serves all-you-can-eat Chinese and Japanese food, as well as Italian and American dishes.
Weng said the apple juice was bought at a local supermarket and he had no idea how it had become contaminated.
Davis was at the restaurant with her brother-in-law, Luis Mercado, and two of her other children, Miguel Mercado, 6, and 7-month-old Anthony Mercado.
A spokesman for Penn State Children's Hospital in nearby Hershey said Richie was in a fair condition today. He is thought to have regained consciousness.