The simple answer is no; gaffa tape will not solve your problem no matter what its strength. There is no simple answer and it will depend on whether the leak is in a supply line or a low pressure system as to what is needed to stop the leak. If possible, the pipework either side of the leak needs to be isolated, that part then drained and a proper repair carried out. If its a compression joint at fault, dismantle the joint and wrap sufficient PTFE tape around the thread, in the direction the nut rotates when tightening it. If its in a length of pipe, after isolating and draining it, you can use an inline union, either compression or soldered.
Roger D, March 2012