The amount of milk that a 2 year old should drink a day is around 2 cups of milk which could be those sippy cups full of milk.
But you can give your 2 year old up to 12 ounces of milk per day but anymore than 12 ounces of milk per day for a 2 year old may not be healthy.
So give the 2 year old 2 cups of milk per day if they want it and then give the 2 year old some healthy juice and water throughout the day as well.
Once your 2 year old gets over the age of 2 then they can drink up to 32 ounces of milk per day and they should also drink other drinks besides milk.