Theoretically GFW can do that, because SSH handshake has fingerprints that can be identified. But it will irritate every administrator on this world.
From a reliable source I heard they only ban SSH/VPN service if they can get a free account for testing. So if you are going to use SSH/VPN, make sure the provider do not serve free trials.
Don't know much about the Great Firewall, but I usually keep a SSH server listening on port 80 on a box, sometimes those hotels and company networks don't let anything other than port 80 outbound, and it has yet to fail me.