If i google something on my itouch will it show on my iphone?

Cause both devices share an icloud acct, & what if i erase the hisory and turned off icloud right after.

It will, in browsing history, but if you delete it it should delete there too.

I don't think that you can retrieve the history if you deleted them. Unless, there are some forensic tools to help with.
You can however retreive the history if you have the iCloud account signed in on both the devices.