Prior to the new contract, Smith's base salary in 2013 was $2.75 million. According to NFLPA documentation, his base salary has now been adjusted down to $1.5 million. The Bills also now have an additional $925,000 in cap space, but that's a net figure that also includes contracts handed out to Antoine Caldwell and Tony Hills (who both have $715,000 deals in place), so Smith's cap savings exceed that figure. Buffalo now has $21.8 million in cap room (again, per NFLPA records).
Spotrac.com has Smith's 2013 cap number at $2.575 million. They also report that in addition to the $1.25 million savings in base salary this year, another $1.6 million was shaved off in 2014, from $3 million to $1.4 million.
Smith, who is currently battling for a reserve roster spot (somewhere in the No. 5 or No. 6 range, in all likelihood, alongside players like undrafted rookie Da'Rick Rogers and Hard Knocks alumnus Chris Hogan), has almost certainly bettered his odds of making the 53-man roster with this restructure.