Ive been working as a dishwasher in illinois for about 7-8months and i lost my job due to marijuana ... can i still file for unemployment?

You can always file. Whether you receive it or not depends on the situation. Were you smoking it while on the job? This could be considered "gross misconduct" and, therefore, you may be ineligible to receive it.

Here is a fact sheet from the government to help you figure out if you qualify http://workforcesecurity.doleta.gov/unemploy/uifactsheet.asp

If you do qualify then you can file with your state. Here's a link that you can find out where to go http://workforcesecurity.doleta.gov/map.asp

I hope that helps.