Can a student get admission in IIT after pursuing diploma? (IF YES THEN HOW/if no why)

Since a diploma or polytechnic student cannot apply for JEE advance , he can only attempt only JEE main which was known as AIEE,so for admissions in IIT institutes one must qualify in JEE advance (i.e IIT-JEE),as JEE main isnt considered for admissions in IIT. This is as per my knowledge if any one