What yield and income can chia give and is it really profitable?

Honest numbers first. Chia yields in India are commonly in the range of about 3 to 6 quintal per acre, with only well managed crops in suitable climate reaching the upper end. On price, chia was very attractive when few grew it, but as area expanded the farm gate price fell sharply, and growers now report a wide and unstable range that is much lower than the early hype. There is no MSP and no guaranteed buyer. So profitability depends entirely on getting a fair price and a buyer, not on yield alone. A good crop with a bad buyer is a loss. Get your own district level price from people who actually sold last year, secure a contract or FPO linkage, and run your cost calculation at the low end of the price range, not the high end, before you commit area.