Same here. No tax on lottery winnings, but interest, regardless of the source, is interest and therefore taxable. Also, money gifts are not taxable, regardless of the amount - as in, the person receiving the gift won't have to declare it as revenue. The contrary is also true, though: any money I give away that is not for registered charity is not tax deductible, I can't declare it as expenses. And it applies only to money; gifting assets, including investments, must be declared and thus are taxable, even if they come from inheritance - inherited cash doesn't have to be declared, but assets do.
So, in this scenario, if I gift money to my parents, this money is not taxable, they can do whatever they want with it, including paying their debt. If they invest this gift, any earnings will be taxable. If they buy assets with the gift, including a house, the asset is taxable. In the end, there are always taxes.