There's no sampler that's gonna give you that realistic of a sound. It's definitely either a studio musician hired by them or built up from sample packs with good sax lines. You can get jazz sample packs really cheap and chop the samples at the right places to arrange them into whatever fits your track. I do it all the time.
You can make a decent midi instrument by carefully putting a real instrument sound on a sampler, but you won't get anything remotely close to this.
