Only as long as the chat immediately connects you to a human and you dont have to click/write through 10 bullshit messages about nothing with some half-assed bot.
Yes this. If your thinking of incorporating live chat then make sure it's backed by humans or at least a way to get to human easily (if your AI bot fails to address the initial question). When you don't have a human available such as outside normal business hours just hide the chat feature, people can use your contact form.
IMHO this is the only acceptable method for having a chat feature on a site.