Gardner was Birmingham's top scorer with 10 goals in his first full season at St. Andrew's following his £3million move from Aston Villa.
But lifelong City fan Gardner is now being linked with a £5million move to Sunderland.
When asked if he is leaving or staying at Blues, Gardner said: "I don't know. It's a difficult one.
"I'm unsure exactly what is happening behind the scenes and what the board are thinking.
"Where are we going, what are we planning to do? I don't know.
"At the end of the day, like every player, you have to think of your career. Everything is up in the air at the moment."
Gardner admits McLeish, who looks set to move to Villa as Gerard Houllier's successor, has been a massive influence.
He said: "For me, Alex McLeish was great. He showed a lot of faith in me, signing me from Villa, and my career moved forward from there.
"It's a sad loss for Birmingham and it's not a good start to the summer.
"The club needs to bring in a manager with the kind of credentials and experience Alex McLeish has. Someone like that would fit the bill."