Elon spoke positively of the potential for nuclear fusion in an interview from about twenty years ago that I can’t find anymore. I’m not aware of him mentioning it since then.
Tesla is about sustainable energy. Solar photovoltaics and batteries were selected as the optimal solution because they win overall.
Nuclear fusion is an extremely sophisticated way of generating heat to vaporize water into steam and drive a turbine to drive an alternator.
Solar, wind and battery electricity costs per kWh are going so low that ALL thermal power stations, including coal, gas, oil, biomass, fission, fusion, geothermal and solar (the mirrors and molten salt kind), are being disrupted and are rapidly facing total obsolescence. It won’t matter if you can generate an infinite supply of steam for $0 by magic. The rest of the cost structure of the power plant, cooling, and the transmission grid will be more than the all-in cost of localized solar panels placed near the load. I mean, endless free steam is basically how Iceland gets electricity and it’s still more expensive than solar is right now in some areas of the world.
Therefore, fusion research is a waste of time and resources as far as I can tell—even if it works perfectly. Maybe centuries from now it’ll be the best option for spacecraft civilizations traveling beyond our Solar System but that is a long way off. I think Tesla correctly picked integrated rooftop solar as the best answer for most cases.