Do they accept Mir cards in Phuket and can I withdraw money?

No, of course they don't accept them, and you can't withdraw money either. Mir cards, due to sanctions, do not work almost anywhere in the world except for a few countries, but Thailand is not among them. Therefore, neither in Phuket nor anywhere in Thailand can you pay with a Mir card or withdraw money from it. Read more about everything you need to know about currencies, money and plastic cards in Thailand here - https://nashaplaneta.net/asia/thai/valuta-dengi-v-tailande

Where to go in Thailand for the first time?
Do I need a category "A" license to rent a motorbike?
Can I exchange rubles in Phuket?
Follow the link, all these questions are discussed in the chat - https://t.me/thailand_travel_chat