Hi, it's hard to say a % because it depends on several factors like the strategy you use and the pairs you trade with.
Some traders win huge amount of money and some traders lose money. The bot is just a tool to automate a trading strategy, so it all depends on the strategy you run, regardless you trade manually or using a bot.
That being said, a lot of people are getting good monthly profits with Gunbot. Obviously running a decent trading strategy and choosing decent pairs to trade with.