I don't have exact numbers as I was not involved with the distribution, but as far as I know, over 95% of the investors claimed their BCC/BCH (we're talking about a group of ~500 people).
That's ~$20,000 USD of investor money left on the table. It seems like CG is being compensated quite well with this fork.
That number is based on usercount, not investment amount, eg an investor with 100
BTC claimed would influence it the same way as one with 0.01
BTC unclaimed.
For reference, the current bankroll is 1649
BTC, of which 1103
BTC // 67% are provided by a group of only 10 people (1358
BTC by a group of 20 people // 82%).
I'd expect the actual number of BCH left unclaimed way below your calculated 65.