I think in the latest season they were pushing the gay innuendos pretty hard... though it actually started mid-season 2 when he states: "Wouldn't it be marvelous if I turned out to be a homosexual?"

But they've been returning to Stewie's evil roots lately which is good. For example in "The Courtship of Stewie's Father" Stewie is once again hellbent on killing his mother and does plenty of evil things to her (Peter even helps him in one scene, tying up Lois and putting her in the trunk of their car before driving it into a lake). Also, in "Sibling Rivalry" Stewie battles it out with his now materialized brother Bertram and they have many exchanges similar to the season 3 episode "Emission Impossible".

So, give or take, Stewie isn't any more gay that he was before the show was cancelled... and I think it will stay ambiuous because it is a fun idea to play around with.