No they don't have the same budget but if this was an issue the 2nd season never would've happened in the first place.
"Shogun" has roughly the same budget and viewership as "Alien Earth" and it's already been renewed for two more seasons.
Also keep in mind we don't know the official viewership for most modern shows. The numbers listed on Wikipedia are same day, which no network has used in years. Ratings now go by Live+(whatever number the network is comfortable with) which is day 1 + however many days of DVR, streaming, etc. the network feels is an accurate representation of a show's success. It varies by network.
Fred.