I have 40 year old tanks that sat empty for 20 years with no leakage issues when I re-set them up. The tanks range from a 40
gal, 2-30 gals and a few 10 gals. While there are never 100% guarantees, unless you see obvious breaks or damage in the silicone, you are probably fine. Keep in mind that the old tanks were made better than many of today's tanks. They used heavier glass, silicone made especially for aquariums and care.