"He'll be in big trouble with the Russians if he cannot repay that debt,"

Yes it's ex Thai president and former Ceo of Manchester City who could find himself in trouble.

According to the Thailand newspaper the Nation

He has borrowed money from Gazprombank, a subsidiary of Russian energy giant Gazprom, and is now having a tough time servicing the debt.
The amount of the loan he took from Gazprombank is not known, but it could be to the tune of US$1.5 billion.

But it gets better for the borrowed money was invested in Dubai and it seems

The only way he can pay off this debt is to get his Bt76 billion back. This amount, which was gained from the sale of his shares in Shin Corp, is currently frozen by the Thai authorities and is now pending the ruling of the Supreme Court's Office for Political Holders. On February 26, the Supreme Court will rule whether he is guilty of corruption. If the Court finds him guilty, it would order a permanent seizure of all of Thaksin's Bt76 billion.