...T7 fisherman on 150% happy is worth to give journals? How much I can earn?
Yes, handing in T6 journals with 150% happiness is the first real step for investment in laborers. The longer you play/turn in journals over time, the more profit you will make. I'm guessing it may take you roughly 2 months or so to break even... after that, everything is profit (assuming you fill the journals yourself).
If you're wanting to use T7 journals (t8 house/furniture/etc), that is also profitable, but takes another 2-3 months to break even.