CannedHedgehogs (SpecialBuddy) and myself (LordofUltima) had a long set of matches in Street Fighter IV, which I recorded along with skype voice chat, for your entertainment. Some gold in these matches, nine parts in total. If you're lucky, you might actually see me play other characters. Playlist is here, embedded below for your convenience.
 
 
So the rule of thumb for Akuma vs. Gen is:

1. Teleport or AA every jump-in (..or else).
   
2. Far Roundhouse over and over again until you pummel him into submission.
3. Teleport some more for good measure, just to be sure.
4. Do not use focus attacks when he is remotely near you.
5. Abuse wake-up game.