What Squaddie77 and Gearhead82 told you is not true. The wheels will fit.
The C7 A6 has a wheel bore size of 66.6mm (you may want to verify that though) while the Accord has a smaller 64.1mm hub size. So that will fit. You'll probably want a set of hub centric rings though to avoid possible wheel vibration issues.
The C7 A6 wheel bolt pattern is 5x112. Those will fit on a car with a 5x114.3 pattern.
The only problem is you won't be able to use the Accord's stock lug nuts for two reasons: (1) they're ball seat while the Audi wheels have a conical seat, and (2) you won't have enough room to get all the lugs on. But this can be solved with wobble lug nuts.