There have been customers asking Slack for Confluence to support Confluence Questions. It looks like this would be possible by polling the Questions REST API for both Server and Cloud versions of the plugin, but it would require a nontrivial amount of effort to implement.
We envision it could post notifications on new questions and answers, being configurable just like the other updates (Pages/Blogposts/Comments) are already.
This issue serves to collect interest from customers that would be interested in this feature. Please let us know in the comments if you'd be using the plugin long-term if it had Confluence Questions support and which version you're using (server/cloud).