The Gmail Android app has been updated to support the ability to save attachments to Drive, much like users are able to do when using desktop web Gmail. This allows users to seamlessly manage and organize their documents while on the go.
How it works: When you get an attachment in Gmail, you can save it to Google Drive using “Save to Drive” option in menu, so you can access and share the attachment from any device.
Tip: When you open the Google Drive app on your mobile device or visit http://drive.google.com, you can find the attachment in “Recent” or “My Drive”.
Learn more about Save Gmail attachments to Google Drive on Android