While I have no numbers I’d think tens of thousands, though many of those would be killed on the field of battle - surrenders not taken. I’m thinking primarily of the Jacobite risings of 1715 and 1745 and the Irish risings of (1795? and) 1798. Those prisoners taken were enslaved or executed, foreign soldiers butchered, and leaders themselves publically drawn and quartered (as class traitors given they tended to be aristocrats or gentry). I understand the West Indies took many Scots after 1645, 1685, 1690, 1716 and 1746. I recall as an example that the entire garrison of Carlisle, over 1000 English jacobites abandoned by the main army, surrendered and were executed. By the end of the 1700s transportation to Australia was available as the alternative to execution or slow death in the ‘Hulks’.
From that I’d be confident that the Congressional Congress and officers of the Continental Army would have been executed once the ‘rebellion’ was quashed and the enlisted men likely divided between branding and being sent to the West Indies. Militating against such actions against the common soldier would be concern at the loss of white-men-colonists (a concern of limited value given maybe 100, 000 men would be involved out of a population of 3 or 4 million) and that, given negro chattel slavery was a going concern and well-developed, it would be dangerous to have white Men enslaved alongside black men (it negates the necessary concept of white as master and black as inferior servant).
I think in practice the main method of eliminating rebels was to kill them quickly, on the battlefield either during or just after battle, or by imprisoning them in the hulks pending trial, during which most died.
The main qualifier seems to me to have been whether the rebellion was destroyed quickly, in which case the rebels were killed en masse, or whether the Crown had difficulty, in which case matters went to trial. As there seems to have rarely been significant battlefield victories and no political victory in the Revolutionary War the widespread massacre or trial of rebels does not seem to have occurred. Instead prisoners were released on parole or imprisoned in the hulks pending peace or exchange. I think the best signposts to a Revolutionary War outcome would be the British victories at Bunker Hill and Charleston. In the former hundreds of rebels were bayoneted rather than captured and the American commanders bodies were mutilated and smashed. In the latter a rebel army was destroyed and forced to surrender. I might be wrong but I think many of them were killed, the leaders imprisoned pending treason trial once the rebellion was crushed, and the survivors imprisoned with a view to their death being of no consequence if it occurred. I am open to the likelihood that better treatment occurred either due to the alliance with European powers or that it was viewed by Parliament as a limited war to reconcile Englishmen to their crown.
I still think, based on the treatment of the Jacobites and Irish that, if the Rebels had been smashed in 1777, the officers and landowners would have been hung for treason and attainted and the enlisted men, being only 25 or 50 thousand, killed on the battlefield or shortly thereafter, with a repeat of Judge Jeffrey’s Bloody Assizes. After all that is what happened in Ireland in later, more modern, times, as well as in Russian Poland, the French Vendee, Spanish Americas, Spano-Mexican Texas (the 1813 filibuster), British India (1857 Sepoy mutiny), etc.
