Basically he's interested in her intelligence. He will ask her later from where she get the information that the casino will go down. And Aria explains that she heard rumor about casino's owner and foreshadow its downfall (actually she know it from her past life).
He also find out about her father's successful fur business is actually Aria's idea. She knew that fur fashion will become trend in the future, so she suggested her stepfather to invest in it with plausible and legitimate reasons. Her stepfather with his businessman instinct asked his butler to do investigation about Aria's hints, and as soon as morning on the next day leave immediately to find fur suppliers.
Rather than how she got the information, he's more interested in how she will use the information. In Asher's word, just because someone knows a lot of information, doesn't mean they're intelligent. He's interested in her, because she knows how to use that information in the right place. He thinks that it's in her nature. Most people, no matter how much information or knowledge they have, don't know how to use it properly.