Was checking out the signal providers on ZuluTrade. Did not do an extensive search and not 100% sure about my math but it seems like the best providers are only making around $20,000 USD per year. A provider with $2,500,000 in followers / $100,000 (one lot) x $10 per pip / 2 (.5 pips per traded lot provider fee) x 365 (days per year) / 2 (one trade every 2 days) = $22,812
That's a bit disappointing if my math is correct but, then again, if people are following your demo account that's still a decent amount of money for taking basically no risk. If you are following your own trades then of course you can make a lot more if your system doesn't break. I think I saw one SP with around 2.5 million who trades about once per day. So I guess he is making around $45,000 but he was the only one I saw at that level.