MAX6966 a suitable sink driver for nixie tubes?
No, that device is not suitable for driving Nixie tubes. When an output is switched off, it will see the full voltage at the output pin.

The datasheet clearly states that


  I/O Port Outputs Are 7V-Rated Open Drain


That falls well short of the 170V you'll be using.

Development of drivers specifically designed for Nixie tubes pretty much reached a dead end with the 74141, but there are some modern parts around that will carry out serial to parallel conversion and drive high voltage open-drain outputs. Look at the Microchip HV5122 or HV5522 for example.