Not exactly... although RFC959 doesnt provide a command to get free disk space some FTP servers do provide extended commands to go beyond the RFC listed commands. Best bet is to check what commands does the FTP server support and if they are any extended commands to get the free disk space.
Но при этом возможны хаки по показу занятого места, например, в приветственном баннере :)
(с) http://channel9.msdn.com/forums/TechOff/255243-how-to-check-free-space-on-disk-using-FTP-client/
