I have a Macbook Air 2021 with Apple Silicon, I have a Canon T7i dsl, and I have a Focusrite scarlett 2i2.
What software can I use to record video from the DSLR and audio from the audio interface at the same time?
OBS https://obsproject.com would be the way to go, it allows you to add external and internal audio and video sources. You just add each source, hit record and away you go.
For your camera, you'll need to download Canon's webcam utility to allow your camera to be an used as a source: https://www.canon.co.uk/cameras/eos-webcam-utility/