How much can I earn as an AirSide Expert?

The amount you can earn is a product of how many chats you have and how much you charge per chat. The amount you charge is entirely up to you and will probably be based on your own popularity and the scarcity of your expertise. 
As a very rough guide, experienced airline pilots charge around $15-$25 per 30 min chats, cabin crew and flight attendents will typically charge a little less but there are some who are very popular (particularly on social media) and who prefer to do only a very limited number of chats each month so they charge naturally charge significantly more. Likewise, we have some very specialized experts (particularly within military aviation) who find that their insights are also in high demand. These experts also command a high rate.
It may take you some time to work out the best price per chat and it will hopefully increase as you build a bigger profile. As you receive more positive reviews and your chats become more entertaining and interesting you will find yourself in higher demand. This is when you can start to increase you rate.