The main thing (since there is the most of it) that a breaker protects is the wire. For 30A that is typically 10 AWG copper cable or individual wires in conduit, for 50A that is typically 6 AWG copper cable, 8 AWG copper individual wires in conduit or 6 AWG aluminum individual wires in conduit.
The second thing is any receptacles or other parts. The 14-30 inlet is almost certainly rated for only 30A.
The last thing is the devices/appliances - i.e., what's at the end of the circuit. This gets interesting. A generator is producing the power, so it realistically can't produce a lot more than 30A if it is rated for 7,000W/30A. It can probably surge a bit (e.g., for motor startup) but that's OK for wires, breakers and everything else too. In addition, the generator very likely has its own over-current protection - e.g., a 30A fuse or breaker on the 30A outlet.
So the big question really is the wire. If you actually have wire that is rated for a 50A circuit then you could, in theory, replace that 30A inlet with a 50A inlet and I think you would be fine. On the other hand, if as is likely the case you only have 30A 10 AWG cable then there is real risk (and code violation) in using a 50A breaker and 50A inlet. That's because the next owner would see 50A inlet and get a bigger generator and overload the wire when in use. But almost nobody upsizes wire unnecessarily, with the exception of using 12 AWG on a 15A circuit, which is fairly common. But 8 AWG on a 30A circuit? Not likely.