I am wondering some ICO's accept only ETH. Some accepts BTC, ETH, LTC and other cryptocurrencies as well. Does accepting more currencies in ICO plays a roles in its success.

Also Ethereum's smart contract are built for accepting only ETH. How other ICO's are accepting multiple cryptocurrencies and pays tokens accordingly? Do they have to maintain a sheet of who pays in what currencies in a sheet and allocate tokens accordingly. It seems to be a hard manual process.