Does my employer matching my contribution to a TFSA count towards my annual TFSA contribution limit?
From the government's perspective, you have one TFSA account, and the limit applies regardless of how the money gets into it.
So be careful that the employer's contribution doesn't cause you to exceed your limit.
And be aware that whatever the employer contributes on your behalf counts as a taxable benefit, so you'll have to pay income tax on that. Your company would normally make the deduction for you, so you won't be surprised in April.
But despite any of that, you still end up with "free" money that you wouldn't otherwise have received, so go for it.