https://bluebulletreport.com/2020/10/05/2020-nhl-draft-rankings/
I'll be basing my math on the above link as I try to figure out a reasonable calculation for dumping Smith's contract. I'll be using the Marc Staal trade as a template.
The Rangers gave up next year's 2nd round pick to dump the entirety of Staal's last deal: I have this pick pegged at around 49th overall, thus a value of 4.48. The key to this dump was not the actual cash-dollars owed, but entirely the cap hit, and I'll approach smith the same way.
Smith has 76.31% the cap hit that Staal did, and is about as bad of a player (no need to correct for how bad Staal is), thus the pick value is going to be determined strictly based on the ratio of their two contracts. The logic follows as such: the cost to dump Smith should be 76.31% the draft pick value of Marc Staal. This results in a pick value of about 3.42, and falls between picks #71 and #72 (the 9th or 10th picks of the 2021 3rd round).
Whether or not the Rangers are going to have immediate access to these picks depends on the standings (really depends on where Buffalo falls). Right now, I'd peg the dump cost as one of the 3rd rounders the Rangers have next season, conditional on which pick is the earliest. You're shedding a 4th rounder here for no reason.