I heard the soft drinks and alcoholic drinks are not included.
Hello rosita, and welcome to cruise-chat.
It is true, a large part of the revenue for mainstream cruise lines is the bar sales. It has been that way for several years now. Only the high-end cruise lines have soda and liquor included in the price - but then they charge a lot more than Celebrity so you are still paying for it no matter which line you cruise with.
Go conservative on the budget and figure $2 per can of soda, $4 per beer, and $7 per cocktail. These are ballpark figures but if you use these numbers you should be close on average to the total bar tab.
Did they tell you about the gratuities for the dining room and cabin staff? You will need to budget for those too since it is not included in the cruise price, and it is essentially the only income these great workers get.