Is an employee who works in an internet cafe frequented by both the righteous and the unrighteous, with the unrighteous being the majority, considered sinful?

If most customers use the internet for wrongdoing, then working to serve them is assisting in sin, according to the Almighty’s verse: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." You must advise those in charge of the shop that they are partners with the customers in sin. If you are unable to change the wrongdoing, then you must leave the job, seeking Allah's pleasure, as the Almighty says: "And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect."