iCloud will not sync contacts from other services such as Google. You can either just add the Gmail account to all your devices and sync them from Google, or you will need to copy them to iCloud. If you want to copy them to iCloud, do the following:
- Go to Settings>iCloud, turn Contacts to Off, choose Delete from My iPhone when prompted (ir you have any contacts in iCloud they will still be in iCloud).
- Download the app My Contacts Backup. Use this to backup the remaining contacts on your phone (from Google) as a vCard attachment to an email that you send to yourself. Confirm that you have received the email.
- Go to Settings>iCloud and turn Contacts back to On.
- Go to Settings>Mail,Contacts,Calendars>Default Account (in the Contacts section), set this to iCloud.
- Go to Settings>Mail,Contacts,Calendars...tap your Gmail account and turn Contacts to Off.
- Open the My Contacts Backup email and tap the attachment to import the Google contacts back to your phone and to iCloud.