My go to setup now that I have next to no coral lol is the Canon 6D and Canon 100 2.8 macro. I am only familiar with Canon, so only can give you some advice in that department. Moving to the 70D from the T5i doesn't really make any sense - you're better off spending the money that you would in that exchange on a macro lens. Both are crop bodies and the only thing that the 70D really is going to get you for reef photography IMO is a bit of an easier time setting white balance potentially, but really either way you are going to need to learn to WB with both bodies, and strictly for reef shooting not too much of a difference. The 70D does have wifi, but rarely are you going to transfer pictures right out of the body to a phone, Flickr, etc. without doing some WB correction (at minimum) in post first. So not that useful for reef photography (and the 6D has wifi, and I occasionally use it for non-reef photos). The 70D does have some very nice features over the T5i that are going to pay off for everyday, family, sport/bird use. As Jerry pointed out, you aren't going to get extreme closeups without a dedicated macro lens. The Tamron 90 that he has, on the used market, is your best bet.
IMO, if you are going to spend money and jump from a crop body (i.e. the T5i or 70D), go to a FF body (i.e. used 5DI or II, or 6D). The improvement in IQ over the reduced reach from the crop sensor is worth it
My advice in closing would be to keep the 5Ti and buy a used Tamron 90 macro. Learn how to WB and take macros with that combination. Then consider upgrading that gear if you like it eventually.