Is it possible to have a successful launch if you don't have an audience?

I don't think so

It could be challenging. On the other hand, it is a great reason to reach out to potential users or people who might be interested and ask them if they want to hear news about the product and be notified on the launch day. I mean, launching as an event could be used as a way to build the audience. But it is the process that should be planned ahead. I love Product Hunt tutorials, by the way. They are really helpful.