How long can DTV holders stay in Thailand and can they live there permanently?

You can technically stay/live in Thailand a little shorter than 6 years in total.

180 days per entry. If you want to maximize your stay, you'll extend each time and only leave and come back at the end of each 360 day. And then you do your absolute last entry the day before your visa expires and get 180 days that you can extend another 180 days for a total of 6 years.

Now, why anyone would do this is beyond me. There are better visas for people who want to live here.

And if you can afford a DTV, you can probably afford to travel sometimes and only use Thailand as a base for a few months at a time.

Maybe they should stop allowing anonymous participants

I just live my normal life, which includes visiting the home country every here and then, sometimes for just a couple of days, sometimes for up to 1 month. That way I almost always have 180 days left every time.

But note I don't travel because of the visa, but because I need to. Even if the DTV would allow me to stay 5 years without any mandatory exit in between, I'd be exiting and reentering anyways. Except for the COVID pandemic, there hasn't been any time on my life that I don't travel somewhere due to leisure, work or personal reasons once every few months.

Didn’t you read the details before you applied?

so what answers you will expect? of couse it s allowed to stay 180days every time you come in. There must be someone live nearly 180 or even just 1day only. Has or has no problems it s quite various and not just about how many days you stay in TH.