Yes. No where at the scale and reach of gmail.

We are also talking about consumer emails (not enterprise / corporate)

Outlook(+Hotmail) is the third most popular email service. Just 3x smaller than the Gmail. It's definitely the same kind of scale.

If you count outlook.com and hotmail.com and live.com and all enterprise email you get someone who is probably pretty close or larger than all gmail and gmail-backed domains, especially by volume.