If you purchase the upcoming Wolfenstein: The New Order, you'll gain access to the upcoming next-gen Doom beta. But, if you were to purchase the new Wolfenstein on the Xbox 360 or PS3, unfortunately, you won't receive access to the beta of Doom.
The access to the next-gen beta of Doom will arrive for PS4, Xbox One and PC gamers. You can take a look at the Wolfenstein FAQ right here which explains it all, but it is a little confusing. If you were to purchase Wolfenstein: The New Order on the PS3, you'll still receive beta access to Doom, but just not on your console. You can take that access to your PC, and use it there if you like.
Wolfenstein: The New Order drops on May 20 for the Xbox 360, Xbox One, PS3, PS4 and PC.