It was a little hard to tell. Jack certainly thought it was easy enough to read, but Jack wasn't exactly the sharpest crayon in the box all the time, and it probably didn't matter much at the moment.
"Yeah, Ianto didn't seem to have any idea what was going on. He did say the Doctor was here, though. If anyone's going to be able to figure out how to get out of here, it's going to be him."