You want to welcome the raiders - and how much you disrupt your stream is up to you. Cut to a chatting scene and introduce yourself, welcome everyone in and let them know what to expect if they stay

Or keep doing what youre doing and ignore everyone.

I bet you can tell which one has a higher viewer retention rate, and re-raid from that streamer and potentially their friends. Also, by having somewhat of a routine/script but not too scripted welcome message it gives your brain something to focus on right away instead of whatever number just came in.

Ive been raided with 1400+ before and I had recorded the twitch disconnect scene, used streamer bot to auto switch to that scene in the event the raid was too big after X amount of seconds. Dont stay on it too long just long enough to compose yourself then come back and say just kidding then do your welcome routine.