There's very little evidence that Beethoven's relationship with Napoleon was anything other than one-sided. Jérôme Bonaparte offered Beethoven a Kappellmeister position in Cassel in 1808 — he instead took a pension from Archduke Rudolf and a consortium of other benefactors to stay in Vienna — but that doesn't necessarily mean that Napoleon himself was even aware of the composer, much less an admirer. It's unlikely that many people outside of Beethoven's immediate circle knew about the drama over the dedication until well after his death — as published, the symphony was dedicated to Prince Lobkowitz, with the subtitle "composed to celebrate the memory of a great man"* — and even today my general feeling is that the whole incident is highly romanticized.

Napoleon was on campaign essentially nonstop from the early 1790s until his final exile on St. Helena in 1815, and when he wasn't actively fighting in the field, he was usually ensconced in Paris fending off assassination attempts and evading other political machinations. In April 1805, around the time of the symphony's premiere, Napoleon was in northern France with the Grande Armée awaiting the opportunity to invade England, and the War of the Third Coalition would begin in earnest less than six months later. Given that context, it's difficult to imagine him skipping back to Vienna — a city in which he absolutely would not have been welcome — just to check out a concert.

It's important to remember that the modern classical music ecosystem was just barely coming together in the early 19th century. During the 2022-23 concert season the Eroica will probably be performed 50-60 times just in the US alone and it's almost universally considered one of the greatest symphonies ever written, but between the 1805 Vienna premiere and Beethoven's death in 1827, it was probably performed less than a dozen times in total worldwide, and it received pretty mixed reviews each time, even after he'd become credibly famous.

* Shaaaaade.