This may just be possible
Let's check the number you're looking at. A human needs about 2,000 calories a day, but without movement we can decrease that number to maybe 1,500, or even less. Multiply that by 365.25 days per solar year, for 8000 years and you end up with 1.789 x 10^13 joules of energy. Or, to put it in better numbers, 1/4 of the total energy of the Little Boy atom bomb. That means we need power. As in, 'nuclear power'. And once we've got a nuclear powered prison, things become a bit easier.
You see, we don't need a space prison because space is really good enough. What we need is just a generation ship. And we've got the perfect place to put it, too. The Earth's L3 Lagrange point. The ship has a small enough mass, and it's thrusters should be able to help self-correct if need be. In addition, the L3 is not one, but 2 AUs away at all times, and the Sun is between your captive and the Earth, so contact is going to be all but impossible.
Now the problem is just air, water, and food. As long as the ship is perfectly (and I mean perfectly) self-contained, it's a closed system, and there's nothing wrong in theory with having all three solved with liberal application of electric power from the nuclear generator and sunlight from the sun. (This question has an answer which seems to indicate as such.)
On a separate note, I hear potatoes are apparently pretty good for this kind of thing. (That was a joke. The amount of space you'd need for potatoes and soil are way too much. You'll probably have to rely on cultured bacteria for that kind of sustenance, which would all need to be specially bred for the purpose, considering that they'd be providing some essential vitamins, minerals, nucleic acids, etc., that you can't make. And we don't have that kind of bacteria now. But it's theoretically possible with modern tech, and that's what counts.)
I haven't done the calculations for whether we could launch a payload like this into space, but the Saturn V has a payload capacity (for trans-lunar orbit) of 50 tons. Most of the weight will be the nuclear generator, which is only going to be a few tons, so it seems doable.
So, now we've got a nuclear-powered satellite, and, since you asked for humane life support, I found these pretty compact memory cards on Amazon. Not as cheap as an external hard drive, but I think it's a bit lighter. Buy a few hundred and stock it with shows, books, games, music, funny cat videos, whatever suits this person's fancy, or will. 8000 years is a long time, interests will probably change.
So, adding them all up together, and we get 'this is crazy enough to work'. So, barely possible with a nuclear-powered self-sustaining generation ship orbiting in L3. On that note, I'd advise launching from Discworld, as one-in-a-million chance happen nine times out of ten there. (Yes, I think it's that improbable. Like I said, theory is good, but something will go wrong.)