Are the questions, marked as duplicates still eligible to earn the badges? For example a 'Notable question' badge?
Yes, they are still eligible.
Views are still counted, you can still star them, and you can still vote on them.
For example, this question recently earned the poster a Stellar Question gold badge, despite being closed for nearly 2 years. And this question was closed as a duplicate over a year ago, but recently qualified for a Famous Question gold badge.
The only thing that would prevent a question from being eligible for score, favourite and view related badges is deletion, although a locked post can no longer be voted on and thus won't be able to gain the votes needed for score-related badges.