Yes, it would be a highly fact-based case. I don’t think the IRS would care too much about this case, though, because the unified credit is so much higher than the amount given to the friend. Of course, if the winner was in a significantly higher tax bracket than the friend or had a very high net worth aside from the winnings, the IRS could take the position that this was an attempt to shift income tax or estate and gift tax obligations to another in order to reduce the overall taxes associated with the winnings.
You mean if it weren’t taken as a lump sum, but spread out over time, I presume. I would think there’d have to be solid evidence for such a charge.