I have three pinhole repairs in the bellows of my 1927 Zeiss-Ikon 250/7 Ideal that were put on in late August of 2004 -- small patches of very thin leather applied with rubber cement -- that get better with time, as the patch material takes the fold of the bellows and is compressed into shape with the camera closed.

I have also repaired the bellows on my post-War Wirgin Auta with liquid electrical tape (too many holes, all in corners, to repair with patches) -- after letting it sit for two weeks, there is no tackiness when closing the camera and it's completely light tight, but it's only been a month since I repaired it, so I can't speak to durability (though since I was able to completely remove this bellows for repair, I reversed it to put unworn material on the side that gets the wear, and can conceivably replace it, possibly with a homemade unit, if/when the other side also wears through -- if I'm still around in another 50 years).

Generally, I'd expect a leather patch applied with appropriate adhesive (and I don't consider rubber cement the best, but it was available and works pretty well on leather -- Pliobond would likely be ideal) to last as well as the original leather on a bellows. The main concern is that pinholes indicate the whole bellows is failing, and are likely to be followed by more of the same. If the camera is worth the expenditure (and nearly any 8x10 is), it might be sensible to consider getting the bellows replaced rather than chance new leaks showing up on the first of 20 sheets on a shoot where you won't see the damage until after the shooting opportunity is gone. At the very least, it would be worth getting in the habit of removing the ground glass and putting a bright light inside the bellows before each day's shooting, to look for additional holes, until you can afford the time and/or money to replace the bellows.