can i empower kayle more than three times to empower ambessa legend?

No — activating Kayle's Empower a 4th time doesn't trigger Ambessa, because nothing happens when it resolves.

Kayle's ability can be activated any number of times ([FAQ #11753]), but once she's at three Empowered statuses she can't be Empowered further — the ability resolves and does nothing (Rules 441.1.c, 827.2). Since Ambessa, Matriarch of War triggers only when something becomes Empowered ("When you empower something else, empower me"), and becoming Empowered is the event game effects reference (Rule 441.2.a), a no-op activation gives you no trigger.

You also don't need to go past three for this anyway: each of Kayle's first three Empower activations is a real event, so each one triggers Ambessa if she isn't already Empowered. To loop her, use her own ability first — "Disempower me, [A], [T]: Ready a unit" — then empower something else (a unit with an available Empower, or Kayle while she's still under three statuses) to re-trigger her.