The simple answer to this question is, no. In general terms a thunderstorm alone will not bring down a plane. Modern aircraft are built to withstand a huge amount of turbulence and contrary to what some people think, the wings aren’t going to break off (the wings are actually not two wings but one large wing that the fuselage of the plane is built around, so they are in fact one of the strongest parts of the plane).
All that said however, it is generally not advisable to fly through a thunderstorm as it would be extremely uncomfortable, and for anyone that wasn’t strapped into their seat, quite dangerous. For that reason, commercial aircraft are fitted with forward looking weather radars. These radars can measure water density in the air and as such can “spot” bad weather and thunderstorms up to 200 miles away. They provide a picture to the pilots so that they can then manoeuvre to avoid.
This is what a read-out on a weather radar looks like. On this display you can see where there are storm cells located indicated by the red areas, surrounded by yellow and further surrounded by green. (Green – light, Yellow – moderate, Red – severe). Flying in daylight it is usually possible to see thunderstorms and avoid them visually but at night and when surrounded by cloud a weather radar becomes a very important piece of kit.