How to Beat Yiga?

To start, he'll protect himself with an invulnerable shield until he prepares to summon and throw rock spheres at you that you can't stop with Stasis. However, since he leaves himself open while summoning, shoot him with a bow to stun him, causing the boulder to drop on him and leave him open to attack.

Is it possible to beat the Yiga clan?

Yes, it's possible to kill all the Yiga after they spot you.

How do you stop a Yiga attack?

You can easilt outrun them or hit them. You can't stop them. See it as an opportunity to get duplex bows. They spawn the most around Rito Village and the Rito Stable area, especially around evening.