Japan invaded Manchuria in 1931, then Eastern China from 1937. The Japanese claimed that they were liberating China from the Western Imperialists, but in fact plundered the country and massacred civilians. Mao Zedong was already the leader of the Chinese Communist Party when this happened (since 1935), and probably learnt his lessons. From 1949, Mao had full control over China, and in 1950, his People's Liberation Army entered the Tibet to "liberate them from the tyranny of the Dalai-Lama and protect Tibet from Western Imperialists", but they plundered the country and massacred civilians. The message was the same, the actions were the same. So, did the Japanese invasion of China influenced Communist China in its dealings with Tibet ?

I believe so. Naturally, humans have always influenced each others throughout history. Japan's colonialism was influenced by Western colonialism. Mao and his early Communist followers were influenced by the Soviets, themselves influenced by Marx and Engels' writings, etc. The world is only the result of unlimited influences. But from where did the Chinese under Mao get their influence in the way they treated Tibet if not from their Eastern neighbours, the Japanese ?