Depends on how much input he had. If he didn't create the actual concept for that particular show, develop the ideas and themes etc then he can't be credited as the 'Creator' of that particular series, even if he helped in some areas.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist