The 26-year-old joined the Championship team until the end of the season from League One outfit Bournemouth in January.
Having gone on to make six appearances under Lee Clark, the striker has confessed that he would be left "buzzing" if he was kept able to join the club on a permanent basis.
"This is a big club, without a doubt the biggest one I have played for," Thomas is quoted as saying by the Birmingham Mail. "I'd be buzzing if the manager came to me at the end of the season and said he wanted to sign me. But it's up to me, I have got to keep on scoring goals and keep on working hard."
Thomas scored his first two goals for the Blues during Saturday's 3-1 win over Derby County.