Tang is a fruit-flavored drink which was originally concocted by the General Foods Corporation food scientist William A. Mitchell in 1957.

Itis sold both in powdered and ready-to-drink forms and they both have similar tastes. The recommended usage of original powdered Tang is two tablespoons per 8 US fluid ounces (240 ml) of water. A single 8 US fl oz (240 ml) serving of Tang provides 9 grams (0.32 oz) of sugar; 40 kilocalories (167 kJ); 100% RDA of vitamin C; 10% RDA of vitamin A, calcium, vitamin E, riboflavin, niacin, and vitamin B6, and no caffeine.

Source Wikipedia

So can guinea pigs drink tang and if they can, how much of it can they drink?

Unfortunately they can’t. Tang is far too sweet for them to drink and really isn’t good for them at all. If they do happen to drink some then they will be fine, but it should not be purposely fed to guinea pigs at all.

If you are looking for something for guinea pigs to drink then stuck to giving them fresh water. This will give them the refreshment that they need.