http://fortune.com/2016/10/28/google-cloud-business-2/ states their "other revenue" was $2.543 billion for its third quarter. A chunk of that is from Cloud. So it is definitely the largest share but not sure if it is quite 80%.
Just to clarify, Snap's S-1 says they're committing $2B over the next five years (specifically, $400M per year) - the number you've provided for Google's "other revenue" is $2.543B just in Q3. Ergo, it's nowhere near 80%. :)