Animations will stop working when you close the game, but you don’t have to worry about your offline earnings, because you will be earning the proper amount according to your current in-game progress. 
However, the game needs to restart animations from a specific visual spot. The game will take your marketing campaign and will apply a percentage of occupancy in your hotel. The more expensive the campaign is, the higher percentage of occupancy you'll get.
Try to invest some in-game money on marketing campaigns to reduce your vacant rooms when you reopen your hotel.