I worked at EA before and at Google now.

EA got better over time (and I worked to avoid game teams where crunch was worse), but I had patches of bad crunch. My longest was 9 months of 60+ hour weeks, 6 days a week, 10+ hours a day. Outside of that, I had a couple of more intense shorter crunches. A couple of 80+ weeks.

At Google, I don't believe I have ever once worked more than 50 hours in a single week. 99% of the time, I'm right at 40. If I stay a bit later, the office looks like a ghost town by 6:30.

It depends on the startup.

If it's well run, you aren't working late every night and every weekend.

If it's run by sociopaths who want to keep their employees in a state of perpetual crisis in order to maximize the value of their shares, it's pretty awful.

I worked 80 hours a week at a startup for about six months where we weren't sure we were getting paid unless we shipped to customers so we had to get things done but I was the only programmer at that time. I worked 12 months in 70+ hours a week crunch on one game project (I found documentation here https://www.gamasutra.com/view/feature/131533/postmortem_bli...) - remember the motivation speech was we had to finish or we were all getting fired but I never felt like it was ever as hard as the startup - it was a larger team effort so I was hardly ever the one thing holding up progress. YMMV.