“I think at some point he probably will be allowed back on and probably should be allowed back on,” he said in an interview with CNBC's "Squawk Box" on Thursday.
Mr Gates did not provide a detailed theory explaining why tech platforms would eventually let him back on, but thought it was likely to eventually happen.
Mr Trump was banned from Facebook, Instagram, Twitter, TikTok and several smaller social media outlets following the insurrection at the Capitol.
Squawk Box host Andrew Ross Sorkin asked Mr Gates if he would restore Mr Trump's access to his social media accounts if he were on the oversight board at Facebook.
Mr Gates noted that Mr Trump used the platforms in "corrosive' ways, but determined that he would give the former president his accounts back regardless.
“It’s weird when you’re, you know, saying that the election was stolen without any facts there. And how corrosive that is,” Mr Gates said. “But I’ll bet they’ll find a way to let him back on.”
Mr Gates also predicted that - now that Mr Trump is no longer in office - people may lose interest in what he has to say.
“You know in a way ... people’s interest in what he says may go down quite a bit,” Mr Gates added. “That’ll be interesting to watch.”
The relevance of Mr Trump's words as a private citizen remains to be seen, but recent polling data suggests that more than half of Republicans still consider the former president the leader of the party.
Since losing his social media accounts, Mr Trump has put out very few official statements.
In one missive, issued in the first days of his post-presidency, Mr Trump released a statement claiming it was from the "office of the former president." The statement appeared designed to mimic an official presidential press release.
The former president participated in his first post-presidency television interview on Wednesday when he called in to Fox News to discuss the death of conservative radio host Rush Limbaugh.
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