Jade Cage is 4-6 for Cage.
GLoRToR I used to think in a similar way as you about the matchup, unfortunately when you play high level cage, (I played Maxter's Cage offline at Toryuken) you can really see where she struggles in the matchup.
REO and @PerfectLegend could not pick up Jade and win tournaments with her. She lacks the tools needed to compete at those levels. She is a GOOD and fun character, but she is not tournament viable. As far as Cage goes, here is my breakdown of why cage wins the matchup.
1)F3 is faster than any of jades strings minus d3 and d1. It stuffs 1,2 and has greater range than 1,2.
2) You cannot keep Cage out with boomerags.
3) Cage's Whiff punishing is so good, that you will be afraid to use Jades spacing against a good cage. One whiffed b2, or u3, and cage is in your face f3'ing you.
4) No gtfo me tool outside of glow. Glow often gets stuffed.
5) Cage is a low hitbox character. 1 whiffs high, 2 whiffs high (sometimes), F2 whiffs high, the only options you have for reliable pressure is d3 and F4. F43 is unsafe and is a free f3 for Cage, F4 shadow kick is duckable, F4 staff grab and rangs become your only options. Blocked d3's are given a free d3. This really limits Jades options.
6) Jade cannot keep up to Cage's damage. If Cage gets the life lead, he can easily make you come to him, which is exactly what he wants you to do.
Jade doesn't have the normals to compete in the matchup. She has the range, but all cage has to do is bait that range out by shuffling in and out.