How does long-term drift impact tilt sensor accuracy, and what calibration techniques can be used to correct it?
Hello, about which tilt sensor do you want to know in specific?
Minimally, with appropriate calibration 
Check out these 3 links that offer some details Tutorial: How to calibrate a compass (and accelerometer) with Arduino | Underwater Arduino Data Loggers
04. FreeIMU Calibration ยท mjs513/FreeIMU-Updates Wiki
Correcting the Balboa magnetometer - Support / Robots - Pololu Forum