No, contacts who have hard bounced do not count towards your Zoho Campaigns subscription plan's contact limit.

What happens to a hard-bounced contact

Once a contact hard bounces, they're automatically removed from your active contacts and moved to a separate bounced contacts list, so you don't accidentally email them again. You can't manually delete these hard-bounced records, but since they're excluded from your active contact count, they don't take up space against your plan's contact limit either.

Soft bounces are treated differently

Soft-bounced contacts remain active, since a soft bounce is only a temporary delivery issue, and can be deleted manually if you choose to.