5% income gross

So if I make a game and for first quarter of it I make $100, does epic take 5% then? Or only when I start to make it at $3000

For each product you make under the EULA, the first $3,000 in gross revenue for that product per quarter will be royalty free. So if your game makes $100 in gross revenue the first quarter, no royalties are owed. If you game makes $4,000 the second quarter, you owe royalties on 5% of the $1,000 over $3,000, or $50.

And if my game make $4000 but one day stops does 5% stop too?

So if your game makes less than $3,000 in the third quarter, you don’t owe any royalties.

So I do stop owning epic royalty fees when sales stop then

Right; if there’s no revenue, there’s no royalties