I read the whitepaper but didn't find any info on this so I would like to ask if the monetha payment system would accept other cryptos besides ether (BTC, LTC, etc)?
We are very pro-Ethereum (actually, Ethereum's acronym is hidden in our name = MonETHa) and with the confidence of Ethereum's future we are not only accepting Ether payments, but also will accept Ethereum based cryptocurrencies.
In regards to Bitcoin acceptance - as you probably know, Bitcoin is not a very scalable technology (at least for now if no other changes occur) with a limited amount of coins which makes the transaction cost and the transaction time increase respectively with an increase in demand. Now more than ever, the community is coming to a consensus that Bitcoin is a store of value, like gold and not a method of payment.
Our strategy is to start with a niche (Ethereum tokens) and grow together with it. After gathering all the necessary data from merchants, clients and the development process we will see which currencies are the most viable and we will act to it accordingly. But the main long-term vision of Monetha is to process fiat to fiat payments through Ethereum blockchain. That would open up the biggest scaling opportunity both for market adoption and the usage of DTRS.