Well, he only needs 5 gallons of beverages. Because he buys two containers of each, however, that means he bought 320 gallons total (I would say). How I got my answer:
There are 8 pints in a gallon (8 x 2)
There are 4 quarts in a gallon (4 x 2)
There are 16 cups in a gallon (16 x 2)
There are 128 ounces in a gallon (128 x 2)
With that being said, we can add these to find the total amount of gallons of beverages Julius bought. 16 + 8 + 8 + 32 + 256 = 320.
Hopefully this helps!