I don't think the amount of sales has that much of an effect if a song goes #1 or not. For instance, Thrift Shop, Can't Hold Us, Set Fire To The Rain, and Just Dance were well over the 500K mark weeks before they ascended to #1 on the Hot 100. The demand was simply just there for those songs.
Even more impressive for Adele since the album was already above the 6-million mark at the time SFttR went #1
I don't think the amount of sales has that much of an effect if a song goes #1 or not. For instance, Thrift Shop, Can't Hold Us, Set Fire To The Rain, and Just Dance were well over the 500K mark weeks before they ascended to #1 on the Hot 100. The demand was simply just there for those songs.
Even more impressive for Adele since the album was already above the 6-million mark at the time SFttR went #1
Which is another reason why I say RHI did pretty well considering the sales that played against it plus it was the 4th single
RHI was already near a million before it was sent to radio, I think. Plus, the album had skyrocketed above 7 million copies due to the Grammys
I still think it would have had a shot in the Hot 100 top ten had it been available for streaming.
That's what I'm worried about with her next upcoming singles. Not sure if her label will release them to streaming since her four singles (except for RITD I think) was not up for streaming.
They have less than a quarter of the airplay and sales as Royals. They won't rapidly rise to #1 next week unless Ryan Tedder releases a nude version of Counting Stars tomorrow.
Next one I wanna see is your lead single 
Which is another reason why I say RHI did pretty well considering the sales that played against it plus it was the 4th single