Really you didn't see this hyperlink?
Here is what they say- Terms of Service, you shall not copy, modify, publish, transmit, distribute, perform, or display any content, nor shall you sell, license, rent, or otherwise use or exploit any content for commercial use or in any way that violates any third party right.
Check the terms page
Here is the link
https://support.giphy.com/hc/en-us/articles/360020027752-GIPHY-User-Terms-of-Service