There is a thing about companies when they set up a payment service, they usually do not like to share with others. While services like Android Pay will let you use virtually anything under the sun to use for payment, Samsung Pay still has some catching up to do, but that seems to be changing.
The Verge is reporting that PayPal will be available soon for payment on Samsung Pay. Currently, you can only use bank accounts, credit cards and gift cards. There will be an update soon that will allow you to use PayPal on your mobile device if you are shaking about using your actual card or just like using PayPal as your online bank.
With a new partnership with Braintree, a PayPal subsidiary, Samsung Pay will be allowed as a payment option for those merchants who use Braintree. The update will be coming soon first to US customers and will eventually have a global rollout.