There is much talk about rigging in all over Pakistan but KPK (where PTI won).
Anyway, with a little math, I've come to conclusion that PTI can't form central gov't despite PMLn giving free 100 seats.
On this page:
National Assembly of Pakistan we see following parties seats allocation.
PML-N - 189 seats
PPP - 46 seats
MQM - 24 seats
JUI-F - 13 seats
Together they make up 272 seats in NA. One needs 172 seats to attain majority in the NA. The reason I include the 5 parties is because of the fight between PTI and them during election 2013. Imran didn't want to take oath from Zardari, they pinned murder charges on MQM, JUI-F being diesel.
So if PML-N decided to give PTI 100 seats,
PTI will have in total 133 seats in NA. They still cannot form a gov't. JI can offer 4, which is 137. This makes them still short of 172, which is 35 seats short. Now we know that the said parties will work together to stop PTI from forming gov't, which means free ministries and whatnot. These parties would never want PTI forming the central gov't.
So yes, we don't need new elections. Imran knows that even if he gets the 4 seats that he always complains about is given to him, he can't make a dent to PML-N.
I must also add that even if some miracle happens and PTI forms a gov't, they will remain relatively powerless. The senate has majority made up of PPP, PML-N and so forth. This means they will have to make compromises like current PML does, such as giving JUI-F ministries or catering to PPP demands (dropping corruption charges or swiss banks etc).