This depends on why you are drinking aloe vera gel. Some people take a small amount 30 ml-60 ml per day to maintain their general well being. Others use it for specific reasons and ailments so drink up to 120 ml or more a day. The average amount is 30-60ml per day. Some people, including the elderly, need less whereas those who are larger framed need more. Note: the ‘serving size’ 8 fl oz printed on the side of the bottle is for nutritional comparison purposes only. It does not mean that 8 fl oz is a recommended amount to drink in one serving.
Also, read – what is the best time to drink aloe vera juice?