As an employer you are not allowed to create a hostile work environment and you can be sued if you do. Just like how as an employer even if you think being gay is a sin, you can't call an employee homophobic slurs because that creates a hostile work environment. In Canada your right to freedom of expression does not allow you to create a hostile work environment, and intentionally misgendering someone can create a hostile work environment. The onus is on you to make a good faith effort, you don't have the right to create a hostile work environment and then say, "but I didn't mean to offend even though this person asked me to use a different pronoun multiple times.