Sadly Fijians are well practised at cleaning up after cyclones - they got hit several times last year. While it's the local populace who will probably suffer for a while, generally the resorts and hotels get back to normal very quickly. The clean up from Evan has already begun.
If you're concerned you should call your accommodation and ask them for an update, and ask them when they expect to be fully operational. If you don't like their answer you should ask them for a refund or to re-schedule to another time. Most businesses will be reasonably happy to keep their customers happy and might agree. You'll probably find that if you go and there is still some inconvenience the hotel will make it up to you in some way (an upgrade maybe??? Just ask).
Be aware that if you decide not to go just because you don't want to you are not automatically entitled to a refund, nor can you claim against your insurance. If the hotel is open and operating as normal i.e. they are providing the service they agreed to give when you paid, then there's no reason to cancel.
Also remember that cyclone season in Fiji is November to April, it's possible that there could be another one at anytime - nothing predicted at the moment, but keep an eye on the weather charts and warnings.
Going to Fiji in January is always a risk.... but personally having been there in March a few years back, and missing Cyclone Thomas by a couple of days, we had a great time and didn't notice any damage. Fiji is great. almost 7 years ago