Once you have SSH Keys configured, you can add some extra security to your server by disabling password authentication for SSH. (Note that if you do lose your private key, this will make the server inaccessible and you will need to contact HostGator to have this re-enabled.)
To disable this setting, you can do the following:
In this file, set the following settings to the following values. If these settings are already in the file, set them to "no" rather than add new lines.
Once this is done, restart the SSH daemon to apply the settings.