Why does Kino think that it would be impossible for Jiya to turn down the Old Gentleman's offer?

At the Old Gentleman's castle, the gardener leads Kino and Jiya inside. Though Kino sadly notes the beauty of the garden and the interior of the castle, seeing no hope that Jiya will not want to stay with the Old Gentleman, Jiya remains silent. They approach the Old Gentleman who is transcribing a poem written by a man from India.