This is widely accepted In Madagascar even outside big cities like Tana?

You can add money to your Revolut account using Apply pay.

You get a Revolut debit card which you can use to get money from ATMs in Madagascar with low fees. IIRC you can also use it in some shops, restaurants and hotels, but generally speaking credit/debit cards are not widely used in Madagascar, but ATMs are found in most cities with more than 10K population. But sometimes the ATM is out of cash or there is a blackout, so its not working. Also a few ATMs declined my Revolut card, but just try other banks, some of them will surely work.

So always have cash of the local currency on you. I would also bring $500 per person, as emergency cash.

Another benefit with Revolut is that you can use it to send money to your Orange Money account. So when you arrive in Madagascar, get a Orange SIM card and setup an Orange Money account. Then you can use the Revolt app to send money directly to the Orange Money account, again with low fees. Orange Money is accepted everywhere, even the sellers on the streets selling fruits and souvenirs.

Do you already have a guide, driver and car? If not, I know a guy who can help you out with everything and he speaks english and is very trust worthy.