What is the ruling on using Facebook for marketing and advertising, knowing the Sharia violations it contains, and is this considered assisting in sin and condoning evil?

Facebook is originally a permissible tool that can be used for the recommended, the permissible, the disliked, or the forbidden. Means are subject to the rulings of their ends. There is no harm in marketing through it as long as it is restricted to what is permissible to sell.