I think he hasn't committed to any number yet.

Unlike the number of Bitcoins in which the number is known in advance, Darkcoins have a maximum theoretical limit of approximately 21.3 million coins by 2050 with a slow issuing curve. However the real number of coins can be reduced to something like 16 or 17 million coins in case the hashrate of the network brings the mining reward lower in the near future.

Initially the plan was to have a theoretical limit of approximately 84 million coins, however due to the initial block reward formula which was aggressively diminishing block rewards without a minimum reward set, it would be near impossible to have more than 10 million coins issued.

Minimum block reward is now set at 5 DRKs per block and instead of using block halving every 4 years, Darkcoin employs a far smoother 7% annual decrease in coins issued per block. The minimum block reward was achieved on May 15th 2014.

Bottom line answer is: The theoretical maximum is close to 22mn but in practice we might not see more than 16-17mn coins due to tremendous difficulty increase very early in the coin's life.