Yes, secondary accounts can count towards the recruiter outfit and loyalty points. To obtain loyalty points when your friend buys premium you earn 1 loyalty for every 6 loyalty points they earn. However, to obtain the outfit it's if they buy anything from the webshop. I simply purchased 10 days of premium for new accounts (that never bought premium before) so it counted for both the outfit and loyalty. Here's how it worked for me:
Invite New Players
Invite your friends to join you in Tibia! You can do so via a link, which you can also send to your friend's email address. You can use this link to invite as many friends as you like, but note that you cannot send more than 25 emails within 24 hours. If your friend does not receive the email, you can send an email again 14 days after your first attempt.
If one of your friends follows the link and creates an account from this link, you as well as your friend can earn a reward. As a welcome gift, your friend will receive a mount which can be used on the first 3 characters on the account within the first 7 days after account creation. If your friend buys a product in the Webshop, you will receive the Recruiter Outfit. By inviting more new players who also purchase a product in the Webshop, you can even earn addons for this outfit. What is more, you will also receive one loyalty point for every six loyalty points your invited friend receives for having Premium status.
Source: Tibia Manual