Can discount codes be applied or prevented to Gift Cards?

By default, discount codes can impact any product including Gift Cards. 

Therefore, if you want to prevent them from being applied over gift cards:

1. If you are on Shopify Plus plan, you can add a script to your checkout, so discount codes can’t be applied to specific products, such as gift cards.
2. If you are on non-Plus plan, when creating a discount code, you can:
   1. Specify it to only apply to specific products or collection. 
   2. OR create a general collection that includes all products, except gift cards. Then set up your discount codes, so they can only be applied to the general collection.