If i do the update for iphone will it erase my pictures and everything i have on my phone?

It should not affect your content...however it is always recommended that you make a backup either in iTunes or in iCloud before pdating.

I've updated several and no loss of data.

You shouldn't lose them because of an update but you could lose them anytime due to loss or theft of the phone, dropping and breaking the phone, hardware failure, software problem, etc, etc, etc. If you value the photos, in addition to iTunes and/or iCloud backup, copying to a computer iOS: Import personal photos and videos from iOS devices to your computer or to a 3rd part service such as Flickr is highly recommended.