what do scientists think about fate and destiny
if scientists think free will is an illusion
because
scientists say there is no scientific evidence for free will
I guess it depends on how you define free will, and so what evidence could support it.
The popular libertarian (dualist) definition I've heard from religious believers, that free will is the ability to make willed choices that are neither random nor determined, seems logically incoherent. I would suspect that most in the 'hard' sciences would find that difficult to swallow - although we humans are very good at compartmentalising.
I know that plenty of scientists (and philosophers) who think the world is deterministic and take a compatibilist approach, i.e. they propose a definition of free will that is compatible with determinism. Whether you think this is effectively saying that free will is an illusion depends on whether or not you can accept the definition or explanation of free will they provide - or how you define 'illusion' in this context; i.e. is it something that is not quite what it appears to be, or is it something that isn't really there at all?
My personal view is that the concept of free will, shorn of any moral or religious baggage, derives from our experience of making unconstrained and uncoerced choices according to our will (wants, desires, goals, preferences, etc.), and is therefore subjective. This means it can be compatible with determinism, because, under determinism, our will is deterministic. You could call it 'Experiential Compatibilism'; I think it's a compelling illusion.
The problem of moral responsibility typically clouds compatibilist positions, as it's hard to see how you can be morally responsible for determined actions. Some compatibilists say they have interpretations that allow moral responsibility - Dennet, for example, seems to have a social utilitarian view of it, i.e. that the concept of moral responsibility has an important social role, so we should employ it regardless; I think this is associated with the idea that culture and society are higher-level, emergent phenomena, so it's reasonable for them to have behavioural rules that are also emergent, i.e. are not found in the individual constituent elements (people); the problem here is that these rules are deemed to apply to the constituent elements... apologies to Dennett if I missed the mark - he's rather opaque at times.
Fate and destiny are a step further, implying prescribed outcomes rather than simple determinism. I'd be surprised if many scientists would admit to a serious belief in fate or destiny.