Well, at this time there has been no official statement from anyone who matters describing which form is more powerful. The only statement we have was from Akira Toriyama about a year before the blue form was even known about in which he states this:
“Simply put, it’s because [the red hair] looks so strong,” said Toriyama. “The color yellow has already been used, and blue isn’t really that strong looking, so visually, red is easy to understand.”
But according to the wiki:
The form, due to the intense training and calm mind needed to acquire it, exceedingly surpasses its predecessor Super Saiyan God, and all of the other Saiyan forms. Despite the form's huge upgrade in power from the original Super Saiyan God, even after training with Whis neither Goku nor Vegeta could challenge Beerus alone.
In Battle of Gods, Whis said that Beerus used 70% of his power while fighting SSG Goku. If SSB was 50x stronger than SSG, it might be very likely that either SSB Goku or Vegeta could defeat Beerus alone given that the 70% thing.