You quote the claim from Caroline Glick's article which, from the context of General Dan Halutz's resignation, was written in 2007. Her claims are similar to those in the 97-page research document “The Million Person Gap” published in 2006 as BESA report No 65.
If you read through BESA, there are essentially three criticisms of the 1997 census figures:
The census numbers included 325,000 individuals who hold Palestinian residency permits, but had been living abroad for more than a year. Personally I would regard this a legitimate criticism of something purporting to be a census
The census numbers included 210,000 Arabs living in Jerusalem. The status of East Jerusalem is incredibly sensitive in Israeli and Palestinian politics, but to me this seems an unreasonable criticism of a Palestinian census, especially when the State of Israel does not regard most of these individuals as its citizens. The BESA 65 authors are on stronger ground in saying that double counting needs to be avoided if adding these numbers to Israeli census numbers which count all residents in Jerusalem.
The BESA 65 report claimed to identify an unexplained 113,000 increase over Israel Central Bureau of Statistics records. They state that voting records in 2005 confirm their analysis. This seems to be the weakest claim: a census is designed to inform administrative estimates rather than the other way round.
In summary, there is a debate over the 1997 Palestinian census figures, but Caroline Glick severely overstated it when she said "In all, the PA added approximately 1.4 million people who did not exist to its population rolls." Even if you add all three points stated in BESA 65, you get less than 0.7 million, and I suspect that a figure half that might be more reasonable.
The rest of Glick's 1.4 million claim depended on other claims in BESA 65 unrelated to the 1997 census, and probably even more debatable. A challenge and rebuttal to this was published in the Israeli magazine Azure in 2007. Much of the debate was political rather than statistical.
For what it is worth, the CIA World Factbook gives population estimates in 2013 of 2,676,740 in the West Bank and 1,763,387 in the Gaza Strip. Allowing for modest natural growth, this looks between the extremes of the positions put forward in 2006/7.