Go to Aus airpower if you want a very thorough discussion of the issues of stealth, LPI radar, missile kinematics, etc. etc.
Suffice to say, Russia produces some very capable aircraft. This should come as no surprise to anyone here. We all know the capabilities of the La-7. We all know the formidable threat the MiGs posed in Vietnam and Korea. They were the first with helmet mounted sights, IRST and thrust vectoring. They were also the first with thrust vectored missiles, multimode missiles, and a bunch of other stuff. When the cold war ended, western pilots got the chance to fly against Mig-29 and Su-27 directly, and were frequently stunned by the result - and let us not forget who keeps the ISS up there nowadays. They have never been slouches at aerospace, however bad their cars have been.
Of course, they were last with stealth, lagged for a long time in avionics and radar and had other various issues. They aren't magic either.
So who will win any particular matchup? Well, who will win when an LA-7 engages a P-51 - an encounter I'm sure all here are quite familiar with. The answer is very much, it depends - who has surprise, who has energy, who understands their plane better, and their adversaries. Modern fighter combat is very complex. The performance of aircraft built at the same technology level will vary based on two things - one the particular design tradeoffs the designers make, and two, how well they manage to package those tradeoffs. The P-39 was a brilliant design poorly executed. The Hurricane was an adequate design very well executed. The Spitfire - history speaks for itself.
The T-50 is twenty years younger than the F22. It's got L-band (stealth defeating radar), the IRST, rear quarter radar (so it can launch and run while still guiding), 3D thrust vectoring, its own stealth, and many other goodies. Do these make it a Raptor killer, or is there a hidden design flaw that makes it a turkey? I wouldn't bet on it. However history has not yet spoken of the F-22 vs the T-50. With luck it never will, and the war will be confined to these pages.
However whoever spoke of Russian production capacity is dead wrong. Sukhoi producing these in partnership with India and is looking to produce 1000 aircraft, with (I believe) 250 for the Indian Airforce and 250 for the Russian.
