Amazon has stated that it will no longer be rewarding those who pre-order Company of Heroes 2 with a Beta key:
As of Tuesday, April 2, the Beta is now live. Customers who pre-ordered up to and including April 1, 2013 will receive their Beta code in 24 hours. Orders made after April 1, 2013 will not receive a Beta code. We apologise for any inconvenience this causes.
Steam on the other hand has “Guaranteed Beta Access, when it is available on Steam*”