Download Plugin from Github --- Will it update through Dashboard?

http://wordpress.org/plugins/wp-modal-login/
https://github.com/colegeissinger/wp-modal-login

I am planning download an old version of a plugin (ex: WP Modal Login) from GitHub, upload it via SFTP, and activate it through WP Admin Dashboard. This plugin is in WordPress.org Plugin Directory as well.

When the plugin author/developer releases an update on wordpress.org directory, will I be able to update this plugin through WordPress Admin Dashboard?

Please respond as soon as possible. Thanks in advance.