The correct answer if you want the tank to be less likely to leak/break is to replace the whole bottom.
An internal patch might be a good option for a temporary repair.
The biggest issue with this is that the glass has been compromised, all it needs to have done is to make a weakness in it it wont take much for it to crack across the bottom if it is stressed at all. So if you stick it on a slightly unlevel stand, or it gets flexed in an earthquake or even just in a random movement/someone walking past etc then it can go. None of the glass used in our tanks is perfect so this is always a risk, a chip or any damage makes it more likely but you would have to buy a lotto ticket if you wanted to try and determine how likely/unlikely it was.