This article explains how to forward Windows Live Hotmail to Gmail using Outlook.com. Microsoft replaced Hotmail with Outlook.com in early 2013, but Outlook.com users can continue to send and receive emails using their Hotmail addresses.
To automatically forward all your new incoming Outlook.com email to your Gmail account:
Sign in to your Outlook.com account.
Click the Settings icon at the top of the screen (it looks like a gear). At the bottom of the Settings pane, click View all Outlook settings to open a full-screen settings window.