Is the "data path cycle" the same thing of the "fetch-decode-execute cycle"?
Data path cycle is not widely used terminology.  I believe Tanenbaum made it up.  I don't have the 5th edition, but if I look up Tanenbaum's slides on Google (for example: http://www.verlab.dcc.ufmg.br/_media/cursos/arquitetura/2011-1/transparencias/tanembaum_4.pdf) it appears that he is using data path cycle to refer to a single clock cycle.  As in "the amount of time for all the signals to propagate all the way through the data path."  Think of it as the amount of time required to perform one micro-instruction.

But Tanenbaum uses a multi-cycle-per-instruction microcoded organization, so the fetch-decode-execute cycle (for instructions rather than microinstructions) usually involves multiple clock cycles.