Can you evoke a creature and then sacrifice it in response to its own evoke trigger to get the enter the battlefield effect?

When you cast a creature spell for its evoke cost, two things happen when it enters the battlefield: any enter-the-battlefield (ETB) triggers trigger, AND the evoke triggered ability also triggers (CR 702.96a). Both of these triggers are placed on the stack at the same time, and the active player orders them (CR 603.3b). Crucially, the ETB effect has already triggered — it does not matter what happens to the creature afterward.

So there is no window between the creature entering and the ETB trigger going on the stack where you could sacrifice it to 'save' the ETB trigger. The ETB trigger is already on the stack regardless. The evoke trigger also goes on the stack, requiring you to sacrifice the creature when it resolves (CR 702.96b). You cannot sacrifice the creature 'in response to itself entering' to somehow dodge the evoke sacrifice — the sacrifice is demanded by the evoke trigger when that resolves.

If you sacrifice the creature in response to the evoke trigger (e.g., by using another effect), the evoke trigger will still resolve but simply won't be able to sacrifice the creature again. The ETB trigger has already resolved (or is already on the stack) and will resolve normally. So sacrificing the creature early does not grant any extra benefit — you still get the ETB effect either way, and you still lose the creature.

Concrete example: You cast Mulldrifter for its evoke cost. It enters the battlefield: the 'draw two cards' ETB trigger and the evoke sacrifice trigger both go on the stack. You order them so that 'draw two cards' resolves first. It resolves, you draw two cards, then the evoke trigger resolves and you sacrifice Mulldrifter. Attempting to sacrifice Mulldrifter 'in response' to the evoke trigger accomplishes nothing extra — you were always going to draw two cards.

In summary, there is no trick here. The ETB effect is guaranteed the moment the creature enters the battlefield, and the evoke trigger will still demand a sacrifice. You cannot manipulate this sequence to gain an advantage beyond what evoke already provides (CR 702.96, CR 603.2).