How do you win a Technology victory because it always ends in the age 21000
and i cant get all the research in at that time

You need to build all the spaceship parts and launch them. If you are having trouble teching up to the required level in the time the game allows you may need to rethink your gameplan. I find a good civ for a tech victory is the Chinese. The extra pop in your first city allows you to start researching tech from turn 1. This is at least 5 turns earlier than a civ that uses a balanced worker set up. Also libraries, unis and any wonders that help science production are your friends. Don't neglect your army though, as as soon as the first spaceship part is sent up, the AI will declare war in an attempt to stop you. Also search the board for tips to do with settler pumps, and specialising cities. Some of them have good advice. Hopefully that advice helps. These boards have quite a bit of good advice, so browse around:D

You need to build all the spaceship parts and launch them. If you are having trouble teching up to the required level in the time the game allows you may need to rethink your gameplan. I find a good civ for a tech victory is the Chinese. The extra pop in your first city allows you to start researching tech from turn 1. This is at least 5 turns earlier than a civ that uses a balanced worker set up. Also libraries, unis and any wonders that help science production are your friends. Don't neglect your army though, as as soon as the first spaceship part is sent up, the AI will declare war in an attempt to stop you. Also search the board for tips to do with settler pumps, and specialising cities. Some of them have good advice. Hopefully that advice helps. These boards have quite a bit of good advice, so browse around:D

does having a number of cities help with science and wealth?

I tend to ignore wealth when going to Alpha Centauri. Maybe if I capture an enemy city, I will make one or two gold producers. The more blue flasks you produce the more you research. More cities produce more flasks, also certain buildings give flask multipliers (library for example)

How long does it take to get to alpha centuri because i launched it in 2994 ad and in the end i go domination victory.