"1914" and "this generation" represent two of the problems facing the WTS.
They are dishonest when they present their method for arriving at October 1914. They reject secular chronology yet they completely depend on secular chronology for their year 539 BCE; they do not know when Jews assembled at the site of the destroyed temple; they do not start their 70 years at the moment Jerusalem's temple was destroyed; they cannot prove when Jews went into Egypt nor can they prove that this event marked the start of the 70 Years, as on on and on. The WTS ends their 70 Years in October, the Jews' seventh month, yet Jerusalem was destroyed in the 5th month, corresponding with August.
Regarding "this generation", contemporary Advent groups apply these words to these times. They start with the conclusion and then look for evidence (this is called "begging the question"). At every time in every age there have been people saying the Divine Intervention would take place in their generation. Russell, for example, dated the Second Coming to take place in the 1870s.
When you read "this generation" in the "synoptic" gospels, you are reading words being addressed to each of their respective communities. Writing about 50 to 70 years after the Jesus-event, they were telling their own community that the Divine Intervention would take place during their time, and that some would still be alive when it takes place.
They were no different than today's "second-comers" or any of the people who lived between their time and ours.
Even Apostle Paul writing to the Thessalonians, comforted them by saying it was about to happen during their lifetime.
Doug