This following Bible Student article, I think, is critical background to understanding why Charles Russell made his 1914 prediction and how his doctrine was embedded in political concerns of the time:
http://agsconsulting.com/articles/zionists.htm
Regarding the significant Land issue, Pastor Russell's position is reflected in a statement he made while Palestine was yet part of the Ottoman (Turkish) Empire. In 1911 he proclaimed:
"The message to them [Jews] now is that the land is theirs -- that their period of chastisement is at an end and that shortly divine blessing will come to them -- not as Christians, but as Jews."
In November 1914 after showing that the "sevenfold" or "seven times" period of gentile possession of the Land (Leviticus 26:23-42) had expired, Pastor Russell said:
"Now we are able to tell them [Jews] that the Gentile Times have expired, and that they may go up and take possession of the land. We do not know how soon they will take possession. According to their faith it will be unto them."
The Pastor also stated that every effort should be made to buy the land from a nearly bankrupt Turkey since if Turkey lost Palestine in the war, it would be a total loss.
When Pastor Russell died October 31, 1916, the Herzl Year Book observed: 10
Russell himself, according to the testimony of the American Jewish Press from the years 1910 to 1916 maintained excellent and friendly relations with the leaders of American Jewry to his last days.
Historians observe that Zionism was at its lowest ebb between 1904 and 1917. But Pastor Russell just before his death was gratified to observe that he did much to revive it. The work of Pastor Russell on behalf of the Jewish People can best he summed up by recognizing that never before had the Jewish People opened their hearts to a Christian minister...And never before had a Christian minister brought such heartening comfort to the Jewish People.