Can wait for confirmation, wichert's comment on the original thread[1] (that I can't link to directly for some reason) mentions the gcloud listing these regions as affected:
"
gcloud tells me:
WARNING: The following zones did not respond: us-west2, us-west2-a, southamerica-east1-c, us-west2-b, southamerica-east1, us-east4-b, us-east4, us-east4-a, northamerica-northeast1-c, northamerica-northeast1-b, us-west2-c, southamerica-east1-b, northamerica-northeast1, southamerica-east1-a, northamerica-northeast1-a, us-east4-c. List results may be incomplete.
Luckily for us eu-west1 seems to be working normally."
So the user's outside these zones may have been unaffected, but if this is accurate it is a large number of users affected
" gcloud tells me:
WARNING: The following zones did not respond: us-west2, us-west2-a, southamerica-east1-c, us-west2-b, southamerica-east1, us-east4-b, us-east4, us-east4-a, northamerica-northeast1-c, northamerica-northeast1-b, us-west2-c, southamerica-east1-b, northamerica-northeast1, southamerica-east1-a, northamerica-northeast1-a, us-east4-c. List results may be incomplete.
Luckily for us eu-west1 seems to be working normally."
So the user's outside these zones may have been unaffected, but if this is accurate it is a large number of users affected
[1] https://news.ycombinator.com/item?id=20077421