I had a gut shot on one of my deer before and it took it forever to die. I felt horrible for making such a bad shot. We didnt not have much of a blood trail to follow up on so it took us a while to find it. It did eventually die which was a reflief to me when we found it.
I found that pic of what a gut shot blood trail looks like, and it usually has a bunch of brown chunky stuff in it as well.