Pelly, well, the original prophecy in sacred Scripture is about the advent and Crucifixion of our Lord Jesus Christ. A week in the original passage refers to a period of seven years and was readily and always understood as such. Our Lord expected the Jєωιѕн people, especially those learned among them, to know the time of their visitation.
The link though is from people who have been repeatedly wrong about this and have just extended their false claim by a year every time they were wrong.
Here is the passage in the Douay Rheims along with commentary from Bishop Challoner,
[24] Seventy weeks are shortened upon thy people, and upon thy holy city, that transgression may be finished, and sin may have an end, and iniquity may be abolished; and everlasting justice may be brought; and vision and prophecy may be fulfilled; and the saint of saints may be anointed. [25] Know thou therefore, and take notice: that from the going forth of the word, to build up Jerusalem again, unto Christ the prince, there shall be seven weeks, and sixty-two weeks: and the street shall be built again, and the walls in straitness of times. [26] And after sixty-two weeks Christ shall be slain: and the people that shall deny him shall not be his. And a people with their leader that shall come, shall destroy the city and the sanctuary: and the end thereof shall be waste, and after the end of the war the appointed desolation. [27] And he shall confirm the covenant with many, in one week: and in the half of the week the victim and the sacrifice shall fall: and there shall be in the temple the abomination of desolation: and the desolation shall continue even to the consummation, and to the end.
[24] Seventy weeks: Viz., of years, (or seventy times seven, that is, 490 years,) are shortened; that is, fixed and determined, so that the time shall be no longer.
[25] From the going forth of the word: That is, from the twentieth year of king Artaxerxes, when by his commandment Nehemias rebuilt the walls of Jerusalem, 2 Esd. 2. From which time, according to the best chronology, there were just sixty-nine weeks of years, that is, 483 years to the baptism of Christ, when he first began to preach and execute the office of Messias.-- Ibid.
[25] In straitness of times: angustia temporum: which may allude both to the difficulties and opposition they met with in building: and to the shortness of the time in which they finished the wall, viz., fifty-two days.
[26] A people with their leader: The Romans under Titus.
[27] In the half of the week: or, in the middle of the week, etc. Because Christ preached three years and a half: and then by his sacrifice upon the cross abolished all the sacrifices of the law.-- Ibid.
[27] The abomination of desolation: Some understand this of the profanation of the temple by the crimes of the Jєωs, and by the bloody faction of the zealots. Others of the bringing in thither the ensigns and standard of the pagan Romans. Others, in fine, distinguish three different times of desolation: viz., that under Antiochus; that when the temple was destroyed by the Romans; and the last near the end of the world under Antichrist. To all which, as they suppose, this prophecy may have a relation.