solution for GIT GUI client for remote SSH

If your server has it enabled, you can use XForwarding to display a GUI executed on the remote machine on your local machine.

On the server-side, this means that you need to have the proper tools installed (e.g., git-gui, which means that you also need Tcl/Tk installed, which means that you also need the X infrastructure installed).

You also must enable Xforwarding, by making sure that you have a line like the following in your /etc/ssh/sshd_config:

X11Forwarding yes

To use that on your local Linux machine, you would usually use the -X flag to enable XForwarding for a given connection:

 shiro@local:~$ ssh -X gituser@gitserver

 gituser@gitserver:~$ cd repo.git
 gituser@gitserver:~/repo.git$ git gui

On your local OS X machine, you would instead use -Y:

 shiro@applejoice:~$ ssh -Y gituser@gitserver

 gituser@gitserver:~$ cd repo.git
 gituser@gitserver:~/repo.git$ git gui

You need an Xserver running on your local machine, in order to use XForwarding. While this is not a problem on Linux (or OS X), it gets complicated for Win32. There are tutorials on the web for setting up and using Xservers under Win32 (e.g., Xming).

Aside from VNC / remote X (which is an obvious solution and therefore not worth putting in an answer), the only alternative I can find is Visual Studio Code's new remote development support.

You can connect to a server via ssh (from within Visual Studio Code), and then Visual Studio Code's Git features work natively. The interface is fairly basic however - in particular there is no history view and you can't rebase, cherry-pick, etc. from the GUI. It's basically for staging commits.

This extension gives you a proper git graph view. It's pretty good.