Each week is 7 years. The 70 weeks are 70 x 7 years = 490 years, which are the time apportioned to Daniel's people, Israel. The 1st 69 weeks end with the cutting off of the Messiah. Then there is a indefinite gap of time not included in the 70 weeks, and thus not apportioned to Israel, followed by the 70th week.

Here is a graph of the 70 weeks. (reference Life-Study of Daniel by Witness Lee.)

Except for 1 generation (~40 years) after Christ's death and resurrection, and probably 1 generation before the Lord's return, the Old Testament does not see the church age. Old Testament prophecy skips over the church age. This ~2,000 year gap is in almost every prophecy of Christ in the Old Testament. Thus, you will not find in the Old Testament such major events in world history as: the fall of Rome, the dark ages, the renaisance-reformation, the discovery of America, or World Wars I and II. Nor will you find the major events in Jewish history during the church age: the Spanish Inquisition, the Holocaust, the rebirth of the nation of Israel, the 1967 6-Day War.  From the destruction of the Temple at Jerusalem in 70 A.D. until, I believe, the Gulf War in 1991, no event was specifically prophesied in the Old Testament.

There is a general mention of this 2,000 year period in the Old Testament. Hosea prophesies of a time when God will temporarily say that Israel is not His people (Hos 1:9-10;2:23). He says that this time will be long, lasting until the "latter days (Hos 3:4-5).  Hosea even says that it will last 2 days (Hos 6:1-2), which is a figure for 2,000 years (2 Pet 3:8; Ps 90:4).

Regarding the church, the Old Testament foretells the birth of the church at the Lord's resurrection (Ps 22:22,30-31) and the pouring out of the Spirit at Pentecost (Joel 2:28-29) , but then no direct words until just before the Lord's return (Zech 13:7b-9). There are however many types and figures of the church such as Eve, Israel, Zion, the tabernacle, lampstand, and temple, but these are different than direct words. For example Genesis tells how Eve was builded from Adam. There was a real Eve and a real Adam. This word speaks directly about the creation of Eve. But also, Adam is a type of Christ, and Eve is a type of the church, showing that only that which comes out of Christ can be Christ's bride to match Christ.