Hi Caritin, Welcome to Cruise-Chat.
As Cruise Fanatic said, it is basically the same on all the mass market cruise lines. I don't drink enough soda for it to impact me. Carnival will allow you to bring "a small quantity" of non-alcoholic beverages on board. I usually bring three or four 16oz. bottles of soda (as they don't sell what I drink) and at least a 12 pack of water, plus a gallon jug, and they don't bat an eye. Of course that's not going to work if you are flying to the port with direct transfers.