In the US, conspiracy to distribute narcotics can carry up to life in prison. The sentence is based on the amount and type of drugs involved in the conspiracy - there is actually a table [1] that determines the offense level (which is then used with another table to determine the sentence [2]). In this case, because of the sheer volume of drugs sold via SR, if found guilty on the drug charges alone (he also faces several others) he would be guaranteed a multi-decade sentence.

Specifically, he's looking at a base offense level of 38, plus 2 points for distribution "through mass-marketing by means of an interactive computer service," for an offense level of 40. If he has no criminal history at all, that puts him in the 292-365 months (~25-30 years) in prison range on the drug charges alone. If he also gets the 2 point enhancement for making "a credible threat to use violence, or directed the use of violence" as has been alleged, then he would automatically be looking at 30 years to life since his offense level would be 42.

[1] http://www.ussc.gov/guidelines-manual/2013/2013-2d11 (see "drug quantity table")

[2] http://www.ussc.gov/guidelines-manual/2013/2013-5asentab