I am trying calculate the IQ path latency using table-12 on page 45 of the AD9957 Data Sheet (Rev C). I would like to know if the N value used in the table is taken directly from the 6-bit CCI Interpolation Rate field of the QDUC mode Profile Register (bits 63:58) or is there some additional interpolation factor that needs added? For example, if I set bits 63:58 to a binary 001100 (12 decimal) is that value what I should be using for N or is there some inherent value that I need to take into account?

Yes, N is the CCI rate interpolation factor per bits 63:58 of the QDUC Profile Register.

You are correct in your assumption that N=12 in the example you provided.