Yes they do continue to earn so long as people can access them.
When hubs are idled they are no longer visible to people who visit your profile page UNLESS you do the following: Go to your profile page. Click on "Edit Profile." Go to almost the bottom of that page where it says "Show only Featured Hubs on my profile:" Click on the 'NO' box and then all of your hubs will be visible again on your profile page, available to anyone who wishes to read them.
Idled hubs earn just the same as before they were idled so long as they are visible. The main difference is that idled hubs are no longer indexed by Google and they will not come up when people Google that subject or even if they put the title into the search box word for word.
Once HP idles Hubs they are not immediately UNindexed by Google. If Google has already recently crawled that hub it will continue to be indexed until Google returns for the next crawl. You will know if your hub is indexed by putting its title in the Google search box. If it doesn't come up, it's not indexed anymore, but if it does come up, which if may well do for a week or two after it's been idled, then obviously it's still indexed.