I have maxed out my heavy armor skill, and enchanting and I'm getting bored with Daedric Armor. How high will I have to fortify my smithing skill to get the same benefit out of glass? I'm not sure how to do the math. My Light Armor skill is 50. If anyone has done this before could you give me some advice?

I think it's going to depend on several things: Do you have the glass armor smithing perk? Are you using the Lord Stone? You are going to need a perk or three in the light armor tree... Agile Defender (1) and Custom Fit at the very least.

You will probably have to fully invest into the light armor defensive bonuses, and buff your smithing beyond level 100 and upgrade.

If you make Fortify Smithing gear through enchanting, it will take less than a full investment of perks... check the Character Design Freedom thread here at the forums:
http://www.gamesas.com/index.php?/topic/1310006-complete-character-design-freedom-damage-resist-caps-and-ridiculous-damage-thread-6/