Transferring Gmail emails to Office 365 account is not an easy task. In this regard, I've recently explored an informative article that explains the detailed procedure of the manual method to migrate Gmail to Office 365 account.
However, If you face any difficulty while performing the manual method then you can also opt for the Gmail Backup Software. This utility provides a user-friendly interface for a great user experience. It facilitates its users to migrate their Gmail emails to Office 365, Hotmail, IMAP, Thunderbird, and many other email clients. Moreover, users can also backup their emails with or without attachment files with the help of this software.