Which has more fiber: prunes or prune juice?!
3.5 ounces of prunes has 7.2g of fiber.
3.5 ounces of prune juice has 1.12g of fiber.
So, eating prunes gives you a lot more fiber than drinking prune juice.
To answer your question "by how many grams of fiber":
1 oz. of prunes has 2.05g of fiber and 1 oz. of prune juice has 0.32g of fiber, so prunes have 1.73 more grams of fiber per ounce than prune juice.
Any whole fruit or veggie will have more fiber than just the juice squeezed from it, so definitely the whole prunes.
The amount of fiber in the juice or in the whole prune would depend on the size eaten, and the type of juicer that's used, etc.
from Wikipedia: "Prunes contain dietary fiber (about 6%, or 0.06 g per gram of prune)."