Cuba doesn’t really celebrate christmas like European or North American countries do. First of all it is not a capitalist country that would spend tons of money on gifts. Christmas might be celebrated with a family in ways such as going out for a dinner or to the church if religious. Some Christmas decorations can be seen in the store windows and around the city. The cathedral of course has a nativity scene. Little kids might be asking for gifts but giving gifts for Christmas is not a tradition in Cuba. Locals are basically laughing at me when I ask if santa comes over, “it’s too hot for him!”
Holidays do have an impact on everyday life though, banks etc will be closed over the holidays, but most offices or services that work for tourists are fully functioning, after all christmas is the peak tourist season. People are getting food ready for the end of the year celebrations, big boxes of chicken, full (alive) turkeys and other meat is been sold on the streets. Another thing that might and will run out of stores is drinks, especially beer and champagne.