Are job orientations supposed to be paid for 6 month contract jobs? My job orientation is 3 weeks Long and is not going to be paid?

Agree with Steph on this. Do check with the necessary contracting party. Most importantly if you have sign on any employment contract, do refer to the terms on the contract to see if there is any specification on a "No-pay" period on employment. If you have mislook and sign on to give consent on this, it is still not the end of the world. Ultimately, if you like the job and think there is great career advancement in future, 3 weeks' of No-Pay may work out well in the long run for you. If you sign under a situation where you were misled or misinformed, you can raise this to the HR and then to the employer to see if they can make some exemption for you. All the best.

I dont think there's a fixed answer to this. For a profit-generating company it makes some sense to not pay you during the time you're learning the skill since you're not making any money for them, but you still money for transport and food and maybe office wear, so I'm surprised they dont even offer some sort of allowance.

A few ways out:
1) did you get this job thru an agency? Maybe check with the agent on payment details. Maybe they reimburse your 3 weeks pay after you complete the orientation?
2) double-check w the company HR. Is there perhaps a basic pay and then some bonus such as commissions?
3) will you be paid handsomely after orientation? Is foregoing 3 weeks of pay actually a very small amount compared to the big picture of what you will earn in years to come? Could be helpful to weigh.