Regrettably, no! This wouldn't be fair and to be honest, it wouldn't be fun either.
However, everything in the game is attainable for free. Moreover, there are numerous things you can do to earn gems and other in-game valuables for free.
- Progressing in the World's nets you milestone rewards.
- Daily Chests sometimes reward you with gems.
- You can earn gems from any run if you get the Treasure Hunter perk.
- Limited-time events may have gem rewards.
Never trust websites or software that promise you free stuff in Mr Autofire (or other games for that matter!). These can be dangerous!