I am not sure if he has really taken any stance on legal immigration. I am confident that it is favorable.
A question is whether IV has really approached Stephen. Lately, I saw Jack Welch on the show. Apparently, every congressmen who appeared on Colbert's show has won the last election.
Here is a thread on comedy central I started on this.
I am damn sure that a lot of law makers (or their staff) enjoy Stephen's antics.
Stephen Colbert CERTAINLY is one of the most influential people in American Media. Especially after he made fun of Bush in front of him at White House Correspondents Dinner.
Man if we (all members of IV) can kick start a debate on legal immigration and direct the debate in a manner that Sen Sessions can be brought to spotlight for his inconsistencies, it would be a major achievement for us. Colbert has been extremely vital in shaping public opinion for democrats this November!