Yes it is possible. Many Tumblr users also repost their GIF packs to other platforms including tweeter, Pinterist or reddit. Perhaps, external platforms still may contain these blogs since at the time when a Tumblr blog is deleted, the content is removed only from the Tumblr website. You are able to search using keywords or the name of the blog on these site. Also, some of the users have another account to reblog the thing on the Tumblr in Instagram or DeviantArt, for example.

Suggested read: https://guideet.com/how-to-see-gif-packs-for-deleted-blogs-tumblr/