It is plainly false to claim that he is going to die during the 4 years of Trump being in office. Please don't lie.
It's quite likely that with the RCP 8.5 climate change model, which could be feasible under a Trump administration since he has stated many times that he wants to increase the use of climate change inducing energy sources, someone who is 25 years old right now could die from climate change's apocalyptic effects when they are a senior. As for 40 years off his life expectancy, that's possible, depending on what life expectancy could be by the time he reaches that age.