Does the mareks virus survive hot composting? I am not positive my chicken has mareks and it didn't spread to the others but I am getting new chicks in a month and I already piled all old beddings to compost
It matters how hot your compost gets.
That said, if it was Marek's, the virus is possibly now in every square inch that your chicken has been in... so it's very likely that it is in places other than the bedding. This is why it can be important to try to puzzle out if it is Marek's or not. Vaccinating your new chicks is a good idea if you are suspicious of Marek's.
Can you tell us why you feel your chicken might have Marek's? Maybe we can puzzle it out.